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Sample records for na tokamake jet

  1. Conceptual analysis of a tokamak reactor with lithium dust jet

    International Nuclear Information System (INIS)

    Kuteev, B.V.; Krylov, S.V.; Sergeev, V.Yu.; Skokov, V.G.; Timokhin, V.M.

    2010-01-01

    The steady-state operation of tokamak reactors requires radiating a substantial part of the fusion energy dissipated in plasma to make more uniform the heat loads onto the first wall and to reduce the erosion of the divertor plates. One of the approaches to realize this goal uses injection of lithium dust jet into the scrape-off layer (SOL). A quantitative conceptual analysis of the reactor parameters with lithium dust jet injection is presented here. The effects of the lithium on the core and SOL plasma are considered. The first results of developing the lithium jet injection technology and its application to the T-10 tokamak are also presented.

  2. Transitions in Al-like, Mg-like and Na-like Kr and Mo, observed in the JET tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Jupen, C; Denne, B; Martinson, I [JET Joint Undertaking, Abingdon, Oxon (UK)

    1990-05-01

    Spectra of highly ionized Kr and Mo, emitted from the JET tokamak plasmas, have been recorded in the region 30-335 A. Detailed analysis of the n=3, {Delta}n=0 transitions in Kr XXIV-XXVI and Mo XXX-XXXII has resulted in a number of new spectral classifications. Some isoelectronic regularities for Al-like and Mg-like ions are discussed. (orig.).

  3. A cross-tokamak neural network disruption predictor for the JET and ASDEX Upgrade tokamaks

    Science.gov (United States)

    Windsor, C. G.; Pautasso, G.; Tichmann, C.; Buttery, R. J.; Hender, T. C.; EFDA Contributors, JET; ASDEX Upgrade Team

    2005-05-01

    First results are reported on the prediction of disruptions in one tokamak, based on neural networks trained on another tokamak. The studies use data from the JET and ASDEX Upgrade devices, with a neural network trained on just seven normalized plasma parameters. In this way, a simple single layer perceptron network trained solely on JET correctly anticipated 67% of disruptions on ASDEX Upgrade in advance of 0.01 s before the disruption. The converse test led to a 69% success rate in advance of 0.04 s before the disruption in JET. Only one overall time scaling parameter is allowed between the devices, which can be introduced from theoretical arguments. Disruption prediction performance based on such networks trained and tested on the same device shows even higher success rates (JET, 86%; ASDEX Upgrade, 90%), despite the small number of inputs used and simplicity of the network. It is found that while performance for networks trained and tested on the same device can be improved with more complex networks and many adjustable weights, for cross-machine testing the best approach is a simple single layer perceptron. This offers the basis of a potentially useful technique for large future devices such as ITER, which with further development might help to reduce disruption frequency and minimize the need for a large disruption campaign to train disruption avoidance systems.

  4. A cross-tokamak neural network disruption predictor for the JET and ASDEX Upgrade tokamaks

    International Nuclear Information System (INIS)

    Windsor, C.G.; Buttery, R.J.; Hender, T.C.; Pautasso, G.; Tichmann, C.

    2005-01-01

    First results are reported on the prediction of disruptions in one tokamak, based on neural networks trained on another tokamak. The studies use data from the JET and ASDEX Upgrade devices, with a neural network trained on just seven normalized plasma parameters. In this way, a simple single layer perceptron network trained solely on JET correctly anticipated 67% of disruptions on ASDEX Upgrade in advance of 0.01 s before the disruption. The converse test led to a 69% success rate in advance of 0.04 s before the disruption in JET. Only one overall time scaling parameter is allowed between the devices, which can be introduced from theoretical arguments. Disruption prediction performance based on such networks trained and tested on the same device shows even higher success rates (JET, 86%; ASDEX Upgrade, 90%), despite the small number of inputs used and simplicity of the network. It is found that while performance for networks trained and tested on the same device can be improved with more complex networks and many adjustable weights, for cross-machine testing the best approach is a simple single layer perceptron. This offers the basis of a potentially useful technique for large future devices such as ITER, which with further development might help to reduce disruption frequency and minimize the need for a large disruption campaign to train disruption avoidance systems

  5. q=1 advanced tokamak experiments in JET and comparison with ASDEX Upgrade

    International Nuclear Information System (INIS)

    Joffrin, E.; Wolf, R.; Alper, B.

    2002-01-01

    The ASDEX Upgrade advanced tokamak scenario with central q close to 1 has been reproduced on JET. For almost identical q profiles, the comparative analysis does show similar features like the fishbone activity and the current profile evolution. In JET, transport analyses indicates that an internal transport barrier (ITB) has been produced. Gradient length criterions based on the ion temperature gradient turbulence stabilization are used to characterize the ITBs in both devices. The trigger of ITBs is associated with rational surfaces in both devices although the underlying physics for this triggering seems different. This experiment has the prospect to get closer to identity experiments between the two tokamaks. (author)

  6. First experimental results with the Current Limit Avoidance System at the JET tokamak

    Energy Technology Data Exchange (ETDEWEB)

    De Tommasi, G. [Associazione EURATOM-ENEA-CREATE, Università di Napoli Federico II, Via Claudio 21, 80125 Napoli (Italy); Galeani, S. [Dipartimento di Informatica, Sistemi e Produzione, Università di Roma, Tor Vergata, Rome (Italy); Jachmich, S. [Association EURATOM-Belgian State, Koninklijke Militaire School - Ecole Royale Militaire, B-1000 Brussels (Belgium); Joffrin, E. [IRFM-CEA, Centre de Cadarache, 13108 Saint-paul-lez-Durance (France); Lennholm, M. [EFDA Close Support Unit, Culham Science Centre, OX14 3DB Abingdon (United Kingdom); European Commission, B-1049 Brussels (Belgium); Lomas, P.J. [Euratom-CCFE, Culham Science Centre, OX14 3DB Abingdon (United Kingdom); Neto, A.C. [Associazione EURATOM-IST, Instituto de Plasmas e Fusao Nuclear, IST, 1049-001 Lisboa (Portugal); Maviglia, F. [Associazione EURATOM-ENEA-CREATE, Via Claudio 21, 80125 Napoli (Italy); McCullen, P. [Euratom-CCFE, Culham Science Centre, OX14 3DB Abingdon (United Kingdom); Pironti, A. [Associazione EURATOM-ENEA-CREATE, Università di Napoli Federico II, Via Claudio 21, 80125 Napoli (Italy); Rimini, F.G. [Euratom-CCFE, Culham Science Centre, OX14 3DB Abingdon (United Kingdom); Sips, A.C.C. [European Commission, B-1049 Brussels (Belgium); Varano, G.; Vitelli, R. [Dipartimento di Informatica, Sistemi e Produzione, Università di Roma, Tor Vergata, Rome (Italy); Zaccarian, L. [CNRS, LAAS, 7 Avenue du Colonel Roche, F-31400 Toulouse (France); Universitè de Toulouse, LAAS, F-31400 Toulouse (France)

    2013-06-15

    The Current Limit Avoidance System (CLA) has been recently deployed at the JET tokamak to avoid current saturations in the poloidal field (PF) coils when the eXtreme Shape Controller is used to control the plasma shape. In order to cope with the current saturation limits, the CLA exploits the redundancy of the PF coils system to automatically obtain almost the same plasma shape using a different combination of currents in the PF coils. In the presence of disturbances it tries to avoid the current saturations by relaxing the constraints on the plasma shape control. The CLA system has been successfully implemented on the JET tokamak and fully commissioned in 2011. This paper presents the first experimental results achieved in 2011–2012 during the restart and the ITER-like wall campaigns at JET.

  7. Plasma jet source parameter optimisation and experiments on injection into Globus-M spherical tokamak

    International Nuclear Information System (INIS)

    Gusev, V.K.; Petrov, Yu.V.; Sakharov, N.V.; Semenov, A.A.; Voronin, A.V.

    2005-01-01

    Results of theoretical and experimental research on the plasma sources and injection of plasma and gas jet produced by the modified source into tokamak Globus-M are presented. An experimental test stand was developed for investigation of intense plasma jet generation. Optimisation of pulsed coaxial accelerator parameters by means of analytical calculations is performed with the aim of achieving the highest flow velocity at limited coaxial electrode length and discharge current. The optimal parameters of power supply to generate a plasma jet with minimal impurity contamination and maximum flow velocity were determined. A comparison of experimental and calculation results is made. Plasma jet parameters are measured, such as: impurity species content, pressure distribution across the jet, flow velocity, plasma density, etc. Experiments on the interaction of a higher kinetic energy plasma jet with the magnetic field and plasma of the Globus-M tokamak were performed. Experimental results on plasma and gas jet injection into different Globus-M discharge phases are presented and discussed. Results are presented on the investigation of plasma jet injection as the source for discharge breakdown, plasma current startup and initial density rise. (author)

  8. Hybrid model for simulation of plasma jet injection in tokamak

    Science.gov (United States)

    Galkin, Sergei A.; Bogatu, I. N.

    2016-10-01

    Hybrid kinetic model of plasma treats the ions as kinetic particles and the electrons as charge neutralizing massless fluid. The model is essentially applicable when most of the energy is concentrated in the ions rather than in the electrons, i.e. it is well suited for the high-density hyper-velocity C60 plasma jet. The hybrid model separates the slower ion time scale from the faster electron time scale, which becomes disregardable. That is why hybrid codes consistently outperform the traditional PIC codes in computational efficiency, still resolving kinetic ions effects. We discuss 2D hybrid model and code with exact energy conservation numerical algorithm and present some results of its application to simulation of C60 plasma jet penetration through tokamak-like magnetic barrier. We also examine the 3D model/code extension and its possible applications to tokamak and ionospheric plasmas. The work is supported in part by US DOE DE-SC0015776 Grant.

  9. Controlled thermonuclear fusion in TOKAMAK type reactors, the European example: Joint European Torus (JET)

    International Nuclear Information System (INIS)

    Paris, P.J.; Yassen, F.; Assis, A.S. de; Raposo, C.

    1988-07-01

    The development of controlled thermonuclear reaction in TOKAMAK type reactors, and the main projects in the world are presented. The main characteristics of the JET (Joint European Torus) program, the perspectives for energy production, and the international cooperation for viable use of the TOKAMAK are analysed. (M.C.K.) [pt

  10. Liquid gallium jet-plasma interaction studies in ISTTOK tokamak

    International Nuclear Information System (INIS)

    Gomes, R.B.; Fernandes, H.; Silva, C.; Sarakovskis, A.; Pereira, T.; Figueiredo, J.; Carvalho, B.; Soares, A.; Duarte, P.; Varandas, C.; Lielausis, O.; Klyukin, A.; Platacis, E.; Tale, I.; Alekseyv, A.

    2009-01-01

    Liquid metals have been pointed out as a suitable solution to solve problems related to the use of solid walls submitted to high power loads allowing, simultaneously, an efficient heat exhaustion process from fusion devices. The most promising candidate materials are lithium and gallium. However, lithium has a short liquid state temperature range when compared with gallium. To explore further this property, ISTTOK tokamak is being used to test the interaction of a free flying liquid gallium jet with the plasma. ISTTOK has been successfully operated with this jet without noticeable discharge degradation and no severe effect on the main plasma parameters or a significant plasma contamination by liquid metal. Additionally the response of an infrared sensor, intended to measure the jet surface temperature increase during its interaction with the plasma, has been studied. The jet power extraction capability is extrapolated from the heat flux profiles measured in ISTTOK plasmas.

  11. ISTTOK tokamak plasmas influence on a liquid gallium jet dynamic behavior

    International Nuclear Information System (INIS)

    Gomes, R.B.; Silva, C.; Fernandes, H.; Duarte, P.; Nedzelskiy, I.; Lielausis, O.; Klyukin, A.; Platacis, E.

    2011-01-01

    The main concern in using free flowing liquid metals in fusion devices is related to their interaction with magnetic fields. On ISTTOK tokamak, liquid gallium jets are injected deep into the plasma along a vertical direction. The influence of the plasma interaction on the jet has been investigated monitoring the liquid metal behavior using a fast frame camera. A radial shift on its trajectory has been detected and found to depend on the toroidal magnetic field magnitude and principally on the plasma position within the chamber. The analysis performed to understand the dynamics of the jet perturbation by the plasma is presented in this paper. The jet surface temperature increase during this interaction has also been measured, using absolutely calibrated multichannel IR sensors, to evaluate the jet power exhaustion capability.

  12. ISTTOK tokamak plasmas influence on a liquid gallium jet dynamic behavior

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, R.B., E-mail: gomes@ipfn.ist.utl.pt [Associacao EURATOM/IST, Instituto de Plasmas e Fusao Nuclear - Laboratorio Associado, Instituto Superior Tecnico, 1049-001 Lisboa (Portugal); Silva, C.; Fernandes, H.; Duarte, P.; Nedzelskiy, I. [Associacao EURATOM/IST, Instituto de Plasmas e Fusao Nuclear - Laboratorio Associado, Instituto Superior Tecnico, 1049-001 Lisboa (Portugal); Lielausis, O.; Klyukin, A.; Platacis, E. [Association EURATOM/University of Latvia, Institute of Solid State Physics, 8 Kengaraga Str., LV-1063 Riga (Latvia)

    2011-08-01

    The main concern in using free flowing liquid metals in fusion devices is related to their interaction with magnetic fields. On ISTTOK tokamak, liquid gallium jets are injected deep into the plasma along a vertical direction. The influence of the plasma interaction on the jet has been investigated monitoring the liquid metal behavior using a fast frame camera. A radial shift on its trajectory has been detected and found to depend on the toroidal magnetic field magnitude and principally on the plasma position within the chamber. The analysis performed to understand the dynamics of the jet perturbation by the plasma is presented in this paper. The jet surface temperature increase during this interaction has also been measured, using absolutely calibrated multichannel IR sensors, to evaluate the jet power exhaustion capability.

  13. High kinetic energy plasma jet generation and its injection into the Globus-M spherical tokamak

    International Nuclear Information System (INIS)

    Voronin, A.V.; Gusev, V.K.; Petrov, Yu.V.; Sakharov, N.V.; Abramova, K.B.; Sklyarova, E.M.; Tolstyakov, S.Yu.

    2005-01-01

    Progress in the theoretical and experimental development of the plasma jet source and injection of hydrogen plasma and neutral gas jets into the Globus-M spherical tokamak is discussed. An experimental test bed is described for investigation of intense plasma jets that are generated by a double-stage plasma gun consisting of an intense source for neutral gas production and a conventional pulsed coaxial accelerator. A procedure for optimizing the accelerator parameters so as to achieve the maximum possible flow velocity with a limited discharge current and a reasonable length of the coaxial electrodes is presented. The calculations are compared with experiment. Plasma jet parameters, among them pressure distribution across the jet, flow velocity, plasma density, etc, were measured. Plasma jets with densities of up to 10 22 m -3 , total numbers of accelerated particles (1-5) x 10 19 , and flow velocities of 50-100 km s -1 were successfully injected into the plasma column of the Globus-M tokamak. Interferometric and Thomson scattering measurements confirmed deep jet penetration and a fast density rise ( 19 to 1 x 10 19 ) did not result in plasma degradation

  14. The critical temperature gradient model of plasma transport: applications to Jet and future tokamaks

    International Nuclear Information System (INIS)

    Rebut, P.H.; Lallia, P.P.; Watkins, M.L.

    1989-01-01

    The diversity and complexity of behaviour in tokamak plasmas place strong constraints on any model attempting a description in terms of a single underlying phenomenon. Assuming that turbulence in the magnetic topology is the underlying phenomenon, specific expressions for electron and ion heat flux are derived from heuristic and dimensional arguments. When used in plasma transport codes, rather satisfactory simulations of experimental results are achieved in different sized tokamaks in various regimes of operation. Predictions are given for the expected performance of JET at full planned power and implications for next step tokamaks are indicated

  15. Fusion Energy-Production from a Deuterium-Tritium Plasma in the Jet Tokamak

    NARCIS (Netherlands)

    Rebut, P. H.; Gibson, A.; Huguet, M.; Adams, J. M.; Alper, B.; Altmann, H.; Andersen, A.; Andrew, P.; Angelone, M.; Aliarshad, S.; Baigger, P.; Bailey, W.; Balet, B.; Barabaschi, P.; Barker, P.; Barnsley, R.; Baronian, M.; Bartlett, D. V.; Baylor, L.; Bell, A. C.; Benali, G.; Bertoldi, P.; Bertolini, E.; Bhatnagar, V.; Bickley, A. J.; Binder, D.; Bindslev, H.; Bonicelli, T.; Booth, S. J.; Bosia, G.; Botman, M.; Boucher, D.; Boucquey, P.; Breger, P.; Brelen, H.; Brinkschulte, H.; Brooks, D.; Brown, A.; Brown, T.; Brusati, M.; Bryan, S.; Brzozowski, J.; Buchse, R.; Budd, T.; Bures, M.; Businaro, T.; Butcher, P.; Buttgereit, H.; Caldwellnichols, C.; Campbell, D. J.; Card, P.; Celentano, G.; Challis, C. D.; Chankin, A. V.; Cherubini, A.; Chiron, D.; Christiansen, J.; Chuilon, P.; Claesen, R.; Clement, S.; Clipsham, E.; Coad, J. P.; Coffey, I. H.; Colton, A.; Comiskey, M.; Conroy, S.; Cooke, M.; Cooper, D.; Cooper, S.; Cordey, J. G.; Core, W.; Corrigan, G.; Corti, S.; Costley, A. E.; Cottrell, G.; Cox, M.; Cripwell, P.; Dacosta, O.; Davies, J.; Davies, N.; de Blank, H.; De Esch, H.; Dekock, L.; Deksnis, E.; Delvart, F.; Dennehinnov, G. B.; Deschamps, G.; Dickson, W. J.; Dietz, K. J.; Dmitrenko, S. L.; Dmitrieva, M.; Dobbing, J.; Doglio, A.; Dolgetta, N.; Dorling, S. E.; Doyle, P. G.; Duchs, D. F.; Duquenoy, H.; Edwards, A.; Ehrenberg, J.; Ekedahl, A.; Elevant, T.; Erents, S.K.; Eriksson, L. G.; Fajemirokun, H.; Falter, H.; Freiling, J.; Freville, F.; Froger, C.; Froissard, P.; Fullard, K.; Gadeberg, M.; Galetsas, A.; Gallagher, T.; Gambier, D.; Garribba, M.; Gaze, P.; Giannella, R.; Gill, R. D.; Girard, A.; Gondhalekar, A.; Goodall, D.; Gormezano, C.; Gottardi, N. A.; Gowers, C.; Green, B. J.; Grievson, B.; Haange, R.; Haigh, A.; Hancock, C. J.; Harbour, P. J.; Hartrampf, T.; Hawkes, N. C.; Haynes, P.; Hemmerich, J. L.; Hender, T.; Hoekzema, J.; Holland, D.; Hone, M.; Horton, L.; How, J.; Huart, M.; Hughes, I.; Hughes, T. P.; Hugon, M.; Huo, Y.; Ida, K.; Ingram, B.; Irving, M.; Jacquinot, J.; Jaeckel, H.; Jaeger, J. F.; Janeschitz, G.; Jankovicz, Z.; Jarvis, O. N.; Jensen, F.; Jones, E. M.; Jones, H. D.; Jones, Lpdf; Jones, S.; Jones, T. T. C.; Junger, J. F.; Junique, F.; Kaye, A.; Keen, B. E.; Keilhacker, M.; Kelly, G. J.; Kerner, W.; Khudoleev, A.; Konig, R.; Konstantellos, A.; Kovanen, M.; Kramer, G.; Kupschus, P.; Lasser, R.; Last, J. R.; Laundy, B.; Laurotaroni, L.; Laveyry, M.; Lawson, K.; Lennholm, M.; Lingertat, J.; Litunovski, R. N.; Loarte, A.; Lobel, R.; Lomas, P.; Loughlin, M.; Lowry, C.; Lupo, J.; Maas, A. C.; Machuzak, J.; Macklin, B.; Maddison, G.; Maggi, C. F.; Magyar, G.; Mandl, W.; Marchese, V.; Marcon, G.; Marcus, F.; Mart, J.; Martin, D.; Martin, E.; Martinsolis, R.; Massmann, P.; Matthews, G.; McBryan, H.; McCracken, G.; McKivitt, J.; Meriguet, P.; Miele, P.; Miller, A.; Mills, J.; Mills, S. F.; Millward, P.; Milverton, P.; Minardi, E.; Mohanti, R.; Mondino, P. L.; Montgomery, D.; Montvai, A.; Morgan, P.; Morsi, H.; Muir, D.; Murphy, G.; Myrnas, R.; Nave, F.; Newbert, G.; Newman, M.; Nielsen, P.; Noll, P.; Obert, W.; Obrien, D.; Orchard, J.; Orourke, J.; Ostrom, R.; Ottaviani, M.; Pain, M.; Paoletti, F.; Papastergiou, S.; Parsons, W.; Pasini, D.; Patel, D.; Peacock, A.; Peacock, N.; Pearce, R. J. M.; Pearson, D.; Peng, J. F.; Desilva, R. P.; Perinic, G.; Perry, C.; Petrov, M.; Pick, M. A.; Plancoulaine, J.; Poffe, J. P.; Pohlchen, R.; Porcelli, F.; Porte, L.; Prentice, R.; Puppin, S.; Putvinskii, S.; Radford, G.; Raimondi, T.; Deandrade, M. C. R.; Reichle, R.; Reid, J.; Richards, S.; Righi, E.; Rimini, F.; Robinson, D.; Rolfe, A.; Ross, R. T.; Rossi, L.; Russ, R.; Rutter, P.; Sack, H. C.; Sadler, G.; Saibene, G.; Salanave, J. L.; Sanazzaro, G.; Santagiustina, A.; Sartori, R.; Sborchia, C.; Schild, P.; Schmid, M.; Schmidt, G.; Schunke, B.; Scott, S. M.; Serio, L.; Sibley, A.; Simonini, R.; Sips, A.C.C.; Smeulders, P.; Smith, R.; Stagg, R.; Stamp, M.; Stangeby, P.; Stankiewicz, R.; Start, D. F.; Steed, C. A.; Stork, D.; Stott, P.E.; Stubberfield, P.; Summers, D.; Summers, H.; Svensson, L.; Tagle, J. A.; Talbot, M.; Tanga, A.; Taroni, A.; Terella, C.; Terrington, A.; Tesini, A.; Thomas, P. R.; Thompson, E.; Thomsen, K.; Tibone, F.; Tiscornia, A.; Trevalion, P.; Tubbing, B.; Vanbelle, P.; Vanderbeken, H.; Vlases, G.; von Hellermann, M.; Wade, T.; Walker, C.; Walton, R.; Ward, D.; Watkins, M. L.; Watkins, N.; Watson, M. J.; Weber, S.; Wesson, J.; Wijnands, T. J.; Wilks, J.; Wilson, D.; Winkel, T.; Wolf, R.; Wong, D.; Woodward, C.; Wu, Y.; Wykes, M.; Young, D.; Young, I. D.; Zannelli, L.; Zolfaghari, A.; Zwingmann, W.

    1992-01-01

    The paper describes a series of experiments in the Joint European Torus (JET), culminating in the first tokamak discharges in deuterium-tritium fuelled mixtures. The experiments were undertaken within limits imposed by restrictions on vessel activation and tritium usage. The objectives were: (i) to

  16. Neutron measurements on the JET tokamak by means of bubble detectors

    International Nuclear Information System (INIS)

    Gherendi, M.; Craciunescu, T.; Pantea, A.; Zoita, V.; Edlington, T.; Kiptily, V.; Popovichev, S.; Murari, A.

    2009-01-01

    Full text: The bubble detectors (superheated fluid detectors - SHFDs) are based on suspensions of superheated fluid droplets which vaporise into bubbles when nucleated by radiation interactions. The active detecting medium is in the form of microscopic (20-50 μm) droplets suspended within an elastic polymer. The bubble detectors are of interest for neutron detection in nuclear fusion devices due to some particular characteristics: - High neutron detection efficiency (counts/unit fluence) that ranges from about 4x10 -2 to 4x10 -5 ; - Almost flat, threshold-type energy response over a broad energy range (10's keV to 10's MeV); - The possibility of having any energy threshold within the above-mentioned energy range; - Practically zero sensitivity to gamma-radiation; - Good spatial resolution (sub-centimetre resolution in the image plane). A series of the neutron measurements have been carried out by means of bubble detectors on the JET tokamak, at Culham Science Centre, Abingdon, UK, during the experimental campaigns C17-C26 (2007-2009). The neutron field parameters (yield, fluence, energy distribution) at a specific location outside the JET Torus Hall have been measured using three types of bubble detectors (BD-PND, DEFENDER, and BDS). The bubble detector measurement location is situated at the end of a vertical collimated line of sight, behind the TOFOR neutron time-of-flight spectrometer. The field-of-view is defined by a variable pre-collimator located on top of the JET tokamak. This paper reports only on the neutron fluence measurements. Spatial (radial and toroidal) distributions of the neutron fluence have been obtained with a two-dimensional array having up to 30 bubble detectors. The operation of the bubble detector array as a neutron pinhole camera having a radial resolution at the JET vacuum chamber mid-plane of about 55 mm was demonstrated in measurements using various openings of the pre-collimator. (authors)

  17. Safety analysis of water cooled components inside the JET thermonuclear fusion tokamak

    International Nuclear Information System (INIS)

    Ageladarakis, P.; O'Dowd, N.; Papastergiou, S.

    1998-04-01

    The transient thermal behaviour of a number of components, installed in the vessel of the world's largest Fusion Tokamak (JET) has been examined with a theoretical model, which simulated normal operational conditions and abnormal scenarios namely: Loss of Coolant Flow; Loss of Torus Vacuum; and combinations. A number of theoretical results related to water and cryogenically cooled devices have been validated by a comprehensive experimental campaign conducted both inside the JET plasma chamber and in a test rig. The performance of water cooled components which may be subjected to boiling or freeze-up risks in case of a Loss of Water Flow event has also been analysed. Time constants of transient temperature changes were determined by the model while protective actions were prescribed in order to safeguard the equipment against associated risks. A completely automatic safety protection system has been designed on the basis of these analyses and implemented in the routine JET operation. During operation of JET the safety code reacted several times within the specified time limits and protected the relevant components during real off-normal events. (author)

  18. Study of the trace tritium content in deuterium plasmas of the JET tokamak based on neutron emission spectroscopy measurements

    Energy Technology Data Exchange (ETDEWEB)

    Ringmar, David

    2001-02-01

    This thesis describes a study of the evolution of the trace tritium content in the JET tokamak. The study is based on measurements of the neutron emission, which were performed with the magnetic proton recoil (MPR) spectrometer. Data analysis procedures used to extract the results are described in some detail. The thesis also describes a simplified theoretical model to calculate the absolute tritium concentration with a comparison to the experimental results. The present study covers the time period 1996-2000 and the evolution of neutron emission spectroscopy (NES) results are compared with information from related diagnostic sources, and used to discuss the important issue of how tritium is retained in the JET tokamak.

  19. Study of the trace tritium content in deuterium plasmas of the JET tokamak based on neutron emission spectroscopy measurements

    International Nuclear Information System (INIS)

    Ringmar, David

    2001-02-01

    This thesis describes a study of the evolution of the trace tritium content in the JET tokamak. The study is based on measurements of the neutron emission, which were performed with the magnetic proton recoil (MPR) spectrometer. Data analysis procedures used to extract the results are described in some detail. The thesis also describes a simplified theoretical model to calculate the absolute tritium concentration with a comparison to the experimental results. The present study covers the time period 1996-2000 and the evolution of neutron emission spectroscopy (NES) results are compared with information from related diagnostic sources, and used to discuss the important issue of how tritium is retained in the JET tokamak

  20. Tokamak devices: towards controlled fusion

    International Nuclear Information System (INIS)

    Trocheris, M.

    1975-01-01

    The Tokamak family is from Soviet Union. These devices were exclusively studied at the Kurchatov Institute in Moscow for more than ten years. The first occidental Tokamak started in 1970 at Princeton. The TFR (Tokamak Fontenay-aux-Roses) was built to be superior to the Russian T4. Tokamak future is now represented by the JET (Joint European Tokamak) [fr

  1. Redeposition effects on the target plates of the JET tokamak

    International Nuclear Information System (INIS)

    Coad, J.P.

    1994-01-01

    Complete tiles from the X-point target region of the JET tokamak can be analysed by ion beam techniques in a special chamber equipped to handle beryllium- and tritium-contaminated samples. From the amounts of deuterium co-deposited during plasma operations, and the pattern of beryllium deposits remaining from regular Be evaporation in the torus, erosion and redeposition effects at the target area can be determined. The largest amounts of net redeposition occur in the 'private zone' and near the inner separatrix. There appears to be a net transfer of material from the outer to the inner strike zone: the data are compared with models for divertor transport. (Author)

  2. A key to improved ion core confinement in the JET tokamak: ion stiffness mitigation due to combined plasma rotation and low magnetic shear.

    Science.gov (United States)

    Mantica, P; Angioni, C; Challis, C; Colyer, G; Frassinetti, L; Hawkes, N; Johnson, T; Tsalas, M; deVries, P C; Weiland, J; Baiocchi, B; Beurskens, M N A; Figueiredo, A C A; Giroud, C; Hobirk, J; Joffrin, E; Lerche, E; Naulin, V; Peeters, A G; Salmi, A; Sozzi, C; Strintzi, D; Staebler, G; Tala, T; Van Eester, D; Versloot, T

    2011-09-23

    New transport experiments on JET indicate that ion stiffness mitigation in the core of a rotating plasma, as described by Mantica et al. [Phys. Rev. Lett. 102, 175002 (2009)] results from the combined effect of high rotational shear and low magnetic shear. The observations have important implications for the understanding of improved ion core confinement in advanced tokamak scenarios. Simulations using quasilinear fluid and gyrofluid models show features of stiffness mitigation, while nonlinear gyrokinetic simulations do not. The JET experiments indicate that advanced tokamak scenarios in future devices will require sufficient rotational shear and the capability of q profile manipulation.

  3. Full power in the European tokamak

    International Nuclear Information System (INIS)

    Lallia, P.P.; Hugon, M.

    1987-01-01

    A new research campaign begins at Jet (Abingdon, UK). At this occasion, authors review and compare the performances of the three big Tokamaks that are currently in competition: Jet, JT60 and TFTR, insisting upon the European one. Conditions of ignition are reviewed together and energy losses are specified. Magnetic configurations used in tokamaks are shown, together with the technological responses brought these last years

  4. LH-power coupling in advanced tokamak plasmas in JET

    International Nuclear Information System (INIS)

    Joffrin, E.; Erents, K.; Gormezano, C.

    2000-02-01

    Lower Hybrid Current Drive (LHCD) is the most efficient tool to generate non-inductive current in tokamak plasmas. In JET, significant modifications of the current profile have been recently achieved in coupling up to 3MW of LH power in optimised shear discharges. However, the improved particle confinement during optimised shear plasmas results in a sharp decrease of the electron density in front the launcher close or below the cut-off density (ne=1.7.10 17 m -3 for f LH =37GHz) and makes difficult the coupling of the LH power. Deuterium gas near the launcher can help to improve the coupling, but has also the effect of increasing the ELM activity leading to the erosion of the internal transport barrier (ITB). Future development of lower hybrid launcher should include the constraints imposed by scenario such as the optimised shear. (author)

  5. Research into controlled fusion in tokamaks

    International Nuclear Information System (INIS)

    Zacek, F.

    1992-01-01

    During the thirty years of tokamak research, physicists have been approaching step by step the reactor breakeven condition defined by the Lawson criterion. JET, the European Community tokamak is probably the first candidate among the world largest tokamaks to reach the ignition threshold and thus to demonstrate the physical feasibility of thermonuclear reaction. The record plasma parameters achieved in JET at H plasma modes due to powerful additional plasma heating and due to substantial reduction of plasma impurities, opened the door to the first experiment with a deuterium-tritium plasma. In the paper, the conditions and results of these tritium experiments are described in detail. The prospects of the world tokamak research and of the participation of Czechoslovak physicists are also discussed. (J.U.) 3 figs., 6 refs

  6. Characterisation, modelling and control of advanced scenarios in the european tokamak jet; Caracterisation, modelisation et controle des scenarios avances dans le tokamak europeen jet

    Energy Technology Data Exchange (ETDEWEB)

    Tresset, G

    2002-09-26

    The advanced scenarios, developed for less than ten years with the internal transport barriers and the control of current profile, give rise to a 'new deal' for the tokamak as a future thermonuclear controlled fusion reactor. The Joint European Torus (JET) in United Kingdom is presently the most powerful device in terms of fusion power and it has allowed to acquire a great experience in these improved confinement regimes. The reduction of turbulent transport, considered now as closely linked to the shape of current profile optimised for instance by lower hybrid current drive or the self-generated bootstrap current, can be characterised by a dimensionless criterion. Most of useful information related to the transport barriers are thus available. Large database analysis and real time plasma control are envisaged as attractive applications. The so-called 'S'-shaped transport models exhibit some interesting properties in fair agreement with the experiments, while the non-linear multivariate dependencies of thermal diffusivity can be approximated by a neural network, suggesting a new approach for transport investigation and modelling. Finally, the first experimental demonstrations of real time control of internal transport barriers and current profile have been performed on JET. Sophisticated feedback algorithms have been proposed and are being numerically tested to achieve steady-state and efficient plasmas. (author)

  7. Latest results from JET

    International Nuclear Information System (INIS)

    Bickerton, R.J.

    1989-01-01

    The Joint European Torus (JET) is a large tokamak designed with the essential objective of obtaining and studying plasmas with parameters close to those envisaged for an eventual power-generating, nuclear-fusion reactor. JET is situated on a site near Abingdon, Oxon, UK. JET is the largest single project of the nuclear fusion research programme of the European Atomic Energy Community (EURATOM). The tokamak started operation in mid 1983 after a five year construction period. The scientific and technical results achieved so far are summarised in this article. (orig.)

  8. Perturbative transport experiments in JET Advanced Tokamak plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Mantica, P.; Gorini, G.; Sozzi, C. [Istituto di Fisica del Plasma, EURATOM-ENEA-CNR Association, Milan (Italy); Imbeaux, F.; Sarazin, Y.; Garbet, X. [Association Euratom-CEA, St. Paul-lez-Durance Cedex (France); Kinsey, J. [Lehigh Univ., Bethlehem, Pennsylvania (United States); Budny, R. [Princeton Plasma Physics Lab, New Jersey (United States); Coffey, I.; Parail, V.; Walden, A. [Euratom/UKAEA Fusion Association, Abingdon, Oxon (United Kingdom); Dux, R. [Max-Planck-Institut fuer Plasmaphysik, Garching (Germany); Garzotti, L. [Istituto Gas Ionizzati, Padova (Italy); Ingesson, C. [FOM-Instituut voor Plasmafysica, Nieuwegein (Netherlands); Kissick, M. [University of California, Los Angeles (United States)

    2003-07-01

    Perturbative transport experiments have been performed in JET Advanced Tokamak plasmas either in conditions of fully developed Internal Transport Barrier (ITB) or during a phase where an ITB was not observed. Transient peripheral cooling was induced by either Laser Ablation or Shallow Pellet Injection and the ensuing travelling cold pulse was used to probe the plasma transport in the electron and, for the first time, also in the ion channel. Cold pulses travelling through ITBs are observed to erode the ITB outer part, but, if the inner ITB portion survives, it strongly damps the propagating wave. The result is discussed in the context of proposed possible pictures for ITB formation. In the absence of an ITB, the cold pulse shows a fast propagation in the outer plasma half, which is consistent with a region of stiff transport, while in the inner half it slows down but shows the peculiar feature of amplitude growing while propagating. The data are powerful tests for the validation of theoretical transport models. (author)

  9. The tokamak as a neutron source

    International Nuclear Information System (INIS)

    Hendel, H.W.; Jassby, D.L.

    1989-11-01

    This paper describes the tokamak in its role as a neutron source, with emphasis on experimental results for D-D neutron production. The sections summarize tokamak operation, sources of fusion and non-fusion neutrons, principal neutron detection methods and their calibration, neutron energy spectra and fluxes outside the tokamak plasma chamber, history of neutron production in tokamaks, neutron emission and fusion power gain from JET and TFTR (the largest present-day tokamaks), and D-T neutron production from burnup of D-D tritons. This paper also discusses the prospects for future tokamak neutron production and potential applications of tokamak neutron sources. 100 refs., 16 figs., 4 tabs

  10. A New Generation of Real-Time Systems in the JET Tokamak

    Science.gov (United States)

    Alves, Diogo; Neto, Andre C.; Valcarcel, Daniel F.; Felton, Robert; Lopez, Juan M.; Barbalace, Antonio; Boncagni, Luca; Card, Peter; De Tommasi, Gianmaria; Goodyear, Alex; Jachmich, Stefan; Lomas, Peter J.; Maviglia, Francesco; McCullen, Paul; Murari, Andrea; Rainford, Mark; Reux, Cedric; Rimini, Fernanda; Sartori, Filippo; Stephen, Adam V.; Vega, Jesus; Vitelli, Riccardo; Zabeo, Luca; Zastrow, Klaus-Dieter

    2014-04-01

    Recently, a new recipe for developing and deploying real-time systems has become increasingly adopted in the JET tokamak. Powered by the advent of x86 multi-core technology and the reliability of JET's well established Real-Time Data Network (RTDN) to handle all real-time I/O, an official Linux vanilla kernel has been demonstrated to be able to provide real-time performance to user-space applications that are required to meet stringent timing constraints. In particular, a careful rearrangement of the Interrupt ReQuests' (IRQs) affinities together with the kernel's CPU isolation mechanism allows one to obtain either soft or hard real-time behavior depending on the synchronization mechanism adopted. Finally, the Multithreaded Application Real-Time executor (MARTe) framework is used for building applications particularly optimised for exploring multi-core architectures. In the past year, four new systems based on this philosophy have been installed and are now part of JET's routine operation. The focus of the present work is on the configuration aspects that enable these new systems' real-time capability. Details are given about the common real-time configuration of these systems, followed by a brief description of each system together with results regarding their real-time performance. A cycle time jitter analysis of a user-space MARTe based application synchronizing over a network is also presented. The goal is to compare its deterministic performance while running on a vanilla and on a Messaging Real time Grid (MRG) Linux kernel.

  11. Characterisation, modelling and control of advanced scenarios in the european tokamak jet; Caracterisation, modelisation et controle des scenarios avances dans le tokamak europeen jet

    Energy Technology Data Exchange (ETDEWEB)

    Tresset, G

    2002-09-26

    The advanced scenarios, developed for less than ten years with the internal transport barriers and the control of current profile, give rise to a 'new deal' for the tokamak as a future thermonuclear controlled fusion reactor. The Joint European Torus (JET) in United Kingdom is presently the most powerful device in terms of fusion power and it has allowed to acquire a great experience in these improved confinement regimes. The reduction of turbulent transport, considered now as closely linked to the shape of current profile optimised for instance by lower hybrid current drive or the self-generated bootstrap current, can be characterised by a dimensionless criterion. Most of useful information related to the transport barriers are thus available. Large database analysis and real time plasma control are envisaged as attractive applications. The so-called 'S'-shaped transport models exhibit some interesting properties in fair agreement with the experiments, while the non-linear multivariate dependencies of thermal diffusivity can be approximated by a neural network, suggesting a new approach for transport investigation and modelling. Finally, the first experimental demonstrations of real time control of internal transport barriers and current profile have been performed on JET. Sophisticated feedback algorithms have been proposed and are being numerically tested to achieve steady-state and efficient plasmas. (author)

  12. Liquid gallium jet as a limiter in tokamak: design of the stand

    International Nuclear Information System (INIS)

    Lielausis, O.; Platacis, E.; Klukins, A.

    2005-01-01

    Full text: Plasma facing surfaces should be considered as the most loaded components of the proposed fusion devices. Load densities (up to 1 GW/m 2 ) would result in unacceptably high levels of thermal stresses and erosion. Solutions have been proposed when plasma is contacting not a solid material but a liquid metal in permanent motion. Usually, because of its low Z-number, lithium is considered as the most compatible with plasma. In the given research gallium is used - an essentially more convenient in practice material, outstanding by its low saturated vapor pressure. On tokamak ISTTOK (Portugal, R=0.46m; a=0.085m; B T =0.45 T; I p =8 kA) it is proposed to replace the existing metallic limiter by a liquid gallium jet. The jet forming nozzle is connected with the constant pressure vessel (at the level 1.3 m) by a 1/4 '' SS tube. For an exact determination of the jets length on the level 0.7 m an electrically controlled flow interrupting valve is installed. The metal is brought up into the pressure vessel by an e.m. pump on permanent magnets. The loop is designed in such a way that the liquid metal remains properly insulated both from the plasma vessel walls as well as from the plasma potential

  13. Local Physics Basis of Confinement Degradation in JET ELMy H-Mode Plasmas and Implications for Tokamak Reactors

    International Nuclear Information System (INIS)

    Budny, R.V.; Alper, B.; Borba, D.; Cordey, J.G.; Ernst, D.R.; Gowers, C.

    2001-01-01

    First results of gyrokinetic analysis of JET [Joint European Torus] ELMy [Edge Localized Modes] H-mode [high-confinement modes] plasmas are presented. ELMy H-mode plasmas form the basis of conservative performance predictions for tokamak reactors of the size of ITER [International Thermonuclear Experimental Reactor]. Relatively high performance for long duration has been achieved and the scaling appears to be favorable. It will be necessary to sustain low Z(subscript eff) and high density for high fusion yield. This paper studies the degradation in confinement and increase in the anomalous heat transport observed in two JET plasmas: one with an intense gas puff and the other with a spontaneous transition between Type I to III ELMs at the heating power threshold. Linear gyrokinetic analysis gives the growth rate, gamma(subscript lin) of the fastest growing modes. The flow-shearing rate omega(subscript ExB) and gamma(subscript lin) are large near the top of the pedestal. Their ratio decreases approximately when the confinement degrades and the transport increases. This suggests that tokamak reactors may require intense toroidal or poloidal torque input to maintain sufficiently high |gamma(subscript ExB)|/gamma(subscript lin) near the top of the pedestal for high confinement

  14. Nanoparticle Plasma Jet as Fast Probe for Runaway Electrons in Tokamak Disruptions

    Science.gov (United States)

    Bogatu, I. N.; Galkin, S. A.

    2017-10-01

    Successful probing of runaway electrons (REs) requires fast (1 - 2 ms) high-speed injection of enough mass able to penetrate through tokamak toroidal B-field (2 - 5 T) over 1 - 2 m distance with large assimilation fraction in core plasma. A nanoparticle plasma jet (NPPJ) from a plasma gun is a unique combination of millisecond trigger-to-delivery response and mass-velocity of 100 mg at several km/s for deep direct injection into current channel of rapidly ( 1 ms) cooling post-TQ core plasma. After C60 NPPJ test bed demonstration we started to work on ITER-compatible boron nitride (BN) NPPJ. Once injected into plasma, BN NP undergoes ablative sublimation, thermally decomposes into B and N, and releases abundant B and N high-charge ions along plasma-traversing path and into the core. We present basic characteristics of our BN NPPJ concept and first results from B and N ions on Zeff > 1 effect on REs dynamics by using a self-consistent model for RE current density. Simulation results of BNQ+ NPPJ penetration through tokamak B-field to RE beam location performed with Hybrid Electro-Magnetic code (HEM-2D) are also presented. Work supported by U.S. DOE SBIR Grant.

  15. Blob/hole formation and zonal-flow generation in the edge plasma of the JET tokamak

    DEFF Research Database (Denmark)

    Xu, G.S.; Naulin, Volker; Fundamenski, W.

    2009-01-01

    The first experimental evidence showing the connection between blob/hole formation and zonal-flow generation was obtained in the edge plasma of the JET tokamak. Holes as well as blobs are observed to be born in the edge shear layer, where zonal-flows shear off meso-scale coherent structures......, leading to disconnection of positive and negative pressure perturbations. The newly formed blobs transport azimuthal momentum up the gradient of the azimuthal flow and drive the zonal-flow shear while moving outwards. During this process energy is transferred from the meso-scale coherent structures...

  16. Development of key fusion technologies at JET

    International Nuclear Information System (INIS)

    2001-01-01

    The recent operational phase in JET in which Deuterium-Tritium fuel was used (DTE1) resulted in record breaking fusion performance. In addition to important contributions in plasma physics, the JET Team has also made major advances in demonstrating the viability of some of the key technologies required for the realisation of future fusion power. Two of the most important technological areas which have been successfully demonstrated in JET are the ITER scale tritium processing plant and the exchange of the divertor and maintenance of the interior of JET by totally remote means. The experiment also provided the first data on tritium retention and co-deposition in a diverted tokamak. Of the 35g of tritium injected into the JET torus, about 6g remained in the tokamak. The amount resides mainly on cool surfaces at the inboard divertor side. The precise, safe and timely execution of the remote handling shutdown proved that the design, function, performance and operational methodology of the RH equipment prepared over the years at JET are appropriate for the successful and rapid replacement of components in an activated tokamak environment. (author)

  17. Development of key fusion technologies at JET

    International Nuclear Information System (INIS)

    1999-01-01

    The recent operational phase in JET in which Deuterium-Tritium fuel was used (DTE1) resulted in record breaking fusion performance. In addition to important contributions in plasma physics, the JET Team has also made major advances in demonstrating the viability of some of the key technologies required for the realisation of future fusion power. Two of the most important technological areas which have been successfully demonstrated in JET are the ITER scale tritium processing plant and the exchange of the divertor and maintenance of the interior of JET by totally remote means. The experiment also provided the first data on tritium retention and co-deposition in a diverted tokamak. Of the 35g of tritium injected into the JET torus, about 6g remained in the tokamak. The amount resides mainly on cool surfaces at the inboard divertor side. The precise, safe and timely execution of the remote handling shutdown proved that the design, function, performance and operational methodology of the RH equipment prepared over the years at JET are appropriate for the successful and rapid replacement of components in an activated tokamak environment. (author)

  18. Characterisation, modelling and control of advanced scenarios in the european tokamak jet

    International Nuclear Information System (INIS)

    Tresset, G.

    2002-01-01

    The advanced scenarios, developed for less than ten years with the internal transport barriers and the control of current profile, give rise to a 'new deal' for the tokamak as a future thermonuclear controlled fusion reactor. The Joint European Torus (JET) in United Kingdom is presently the most powerful device in terms of fusion power and it has allowed to acquire a great experience in these improved confinement regimes. The reduction of turbulent transport, considered now as closely linked to the shape of current profile optimised for instance by lower hybrid current drive or the self-generated bootstrap current, can be characterised by a dimensionless criterion. Most of useful information related to the transport barriers are thus available. Large database analysis and real time plasma control are envisaged as attractive applications. The so-called 'S'-shaped transport models exhibit some interesting properties in fair agreement with the experiments, while the non-linear multivariate dependencies of thermal diffusivity can be approximated by a neural network, suggesting a new approach for transport investigation and modelling. Finally, the first experimental demonstrations of real time control of internal transport barriers and current profile have been performed on JET. Sophisticated feedback algorithms have been proposed and are being numerically tested to achieve steady-state and efficient plasmas. (author)

  19. Tokamak experiments

    International Nuclear Information System (INIS)

    Robinson, D.C.

    1987-01-01

    With the advent of the new large tokamaks JET, JT-60 and TFTR important advances in magnetic confinement have been made. These include the exploitation of radio frequency and neutral beam heating on a much larger scale than previously, the demonstration of regimes of improved confinement and the demonstration of current drive at the Megamp level. A number of small and medium sized tokamaks have also come into operation recently such as WT-3 in Japan with an emphasis on radio frequency current drive and HL-1 a medium sized tokamak in China. Each of these new tokamaks is addressing specific problems which remain for the future development of the system. Of these particular problems: β, density and q limits remain important issues for the future development of the tokamak. β limits are being addressed on the DIII-D device in the USA. The anomalous confinement that the tokamak displays is being explored in detail on the TEXT device in the USA. Two other problems are impurity control and current drive. There is significant emphasis on divertor configurations at the present time with their enhanced confinement in the so called H mode. Due to improved discharge cleaning techniques and the ability to repetitively refuel using pellets, purer plasmas can be obtained even without divertors. Current drive remains a crucial issue for quasi of near steady state operation of the tokamak in the future and many current drive schemes are being investigated. (author) [pt

  20. Development on JET of Advanced Tokamak Operations for ITER

    International Nuclear Information System (INIS)

    Tuccillo, A.A.; Crisanti, F.; Litaudon, X.

    2005-01-01

    Recent research on Advanced Tokamak in JET has focused on scenarii with both monotonic and reversed shear q profiles having plasma parameters as relevant as possible for extrapolation to ITER. Wide ITBs, R∼3.7m, are formed at ITER relevant triangularity δ∼0.45, with n e /n G ∼60% and ELMs moderated by Ne injection. At higher current (I P ≤3.5MA, δ∼0.25) wide ITBs sitting at R≥ 3.5m (positive shear region) have been developed, generally MHD events terminate these barrier otherwise limited in strength by power availability. ITBs with core density close to Greenwald value are obtained with plasma target preformed by opportune timing of LHCD, pellet injection and small amount of NBI power. ITB start with toroidal rotation 4 times lower than the standard NBI heated ITBs. Full CD is achieved in reversed shear ITBs at 3T/1.8 MA, by using 10MW NBI, 5MW ICRH and 3MW LH. Wide ITBs located at R=3.6m, without impurity accumulation and type-III ELMs edge can be sustained for a time close to neo-classical resistive time. These discharges have been extended to the maximum duration allowed by subsystems (20s) with the JET record of injected energy: E∼330 MJ. Integrated control of pressure and current profile isit; feature used in these discharges. Central ICRF mode conversion electron heating, added to about 14MW NBI power, produced impressive ITBs with equivalent Q DT ∼ 0.25. Conversely ion ITBs are obtained with low torque injection, by ICRH 3 He minority heating of ions, on pure LHCD electron ITBs. Similarity experiments between JET and AUG have compared the dynamics of ITBs and have been the starting point of Hybrid Scenarios activity, then developed at ρ* as low as ρ*∼3*10 -3 . The development of hybrid regime with dominant electron heating has also started. Injection of trace of tritium and a mixture of Ar/Ne allowed studying fuel and impurities transport in many of the explored AT scenarios. (author)

  1. Transient heat transport studies in JET conventional and advanced tokamak plasmas

    International Nuclear Information System (INIS)

    Mantica, P.; Coffey, I.; Dux, R.

    2003-01-01

    Transient transport studies are a valuable complement to steady-state analysis for the understanding of transport mechanisms and the validation of physics-based transport models. This paper presents results from transient heat transport experiments in JET and their modelling. Edge cold pulses and modulation of ICRH (in mode conversion scheme) have been used to provide detectable electron and ion temperature perturbations. The experiments have been performed in conventional L-mode plasmas or in Advanced Tokamak regimes, in the presence of an Internal Transport Barrier (ITB). In conventional plasmas, the issues of stiffness and non-locality have been addressed. Cold pulse propagation in ITB plasmas has provided useful insight into the physics of ITB formation. The use of edge perturbations for ITB triggering has been explored. Modelling of the experimental results has been performed using both empirical models and physics-based models. Results of cold pulse experiments in ITBs have also been compared with turbulence simulations. (author)

  2. JET Joint Undertaking

    International Nuclear Information System (INIS)

    Keen, B.E.; Kupschus, P.

    1984-09-01

    The report is in sections, as follows. (1) Introduction and summary. (2) A brief description of the origins of the JET Project within the EURATOM fusion programme and the objectives and aims of the device. The basic JET design and the overall philosophy of operation are explained and the first six months of operation of the machine are summarised. The Project Team Structure adopted for the Operation Phase is set out. Finally, in order to set JET's progress in context, other large tokamaks throughout the world and their achievements are briefly described. (3) The activities and progress within the Operation and Development Department are set out; particularly relating to its responsibilities for the operation and maintenance of the tokamak and for developing the necessary engineering equipment to enhance the machine to full performance. (4) The activities and progress within the Scientific Department are described; particularly relating to the specification, procurement and operation of diagnostic equipment; definition and execution of the programme; and the interpretation of experimental results. (5) JET's programme plans for the immediate future and a broad outline of the JET Development Plan to 1990 are given. (author)

  3. The JET project: introduction and background

    International Nuclear Information System (INIS)

    Pease, R.S.

    1987-01-01

    The Joint European Torus, JET, is an experiment, undertaken by 15 partners from 12 nations of Western Europe, to get information on the magnetic confinement of high-temperature plasma in conditions close to those needed for energy-producing controlled thermonuclear fusion reactors. Physically, JET is a very powerful toroidal-pinch electric discharge in a strong stabilizing magnetic field, a system known as a tokamak. The paper summarizes the main features of a tokamak and relates them to the papers in this symposium. (author)

  4. Disruption generated secondary runaway electrons in present day tokamaks

    International Nuclear Information System (INIS)

    Pankratov, I.M.; Jaspers, R.

    2000-01-01

    An analysis of the runaway electron secondary generation during disruptions in present day tokamaks (JET, JT-60U, TEXTOR) was made. It was shown that even for tokamaks with the plasma current I approx 100 kA the secondary generation may dominate the runaway production during disruptions. In the same time in tokamaks with I approx 1 MA the runaway electron secondary generation during disruptions may be suppressed

  5. Plasma performance of TFCX and JET with sawtoothing

    International Nuclear Information System (INIS)

    Hively, L.M.; Mikkelsen, D.R.

    1984-11-01

    The plasma performance is assessed for two tokamak reactor experiments, the Tokamak Fusion Core Experiment (TFCX) and the Joint European Torus (JET). Both machines appear ignitable for a reasonable range of transport assumptions

  6. Overview of Tokamak Results

    International Nuclear Information System (INIS)

    Unterberg, Bernhard; Samm, Ulrich

    2004-01-01

    An overview is given of recent results obtained in tokamak devices. We introduce basic confinement scenarios as L-mode, H-mode and plasmas with an internal transport barrier and discuss methods for profile control. Important findings in DT-experiments at JET as α-particle heating are described. Methods for power exhaust like plasma regimes with a radiating mantle and radiative divertor scenarios are discussed. The overall impact of plasma edge conditions on the general plasma performance in tokamaks is illustrated by describing the impact of wall conditions on confinement and the edge operational diagram of H-mode plasmas

  7. Neutronic analysis of JET external neutron monitor response

    Energy Technology Data Exchange (ETDEWEB)

    Snoj, Luka, E-mail: luka.snoj@ijs.si [Reactor Physics Division, Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Lengar, Igor; Čufar, Aljaž [Reactor Physics Division, Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Syme, Brian; Popovichev, Sergey [Culham Centre for Fusion Energy, Culham Science Centre, Abingdon, OX14 3DB, United Kingdom (United Kingdom); Batistoni, Paola [ENEA C. R. Frascati, via E. Fermi 45, 00044 Frascati, Roma (Italy); Conroy, Sean [VR Association, Uppsala University, Department of Physics and Astronomy, PO Box 516, SE-75120 Uppsala (Sweden)

    2016-11-01

    Highlights: • We model JET tokamak containing JET remote handling system. • We investigate effect of remote handling system on external neutron monitor response. • Remote handling system correction factors are calculated. • Integral correction factors are relatively small, i.e up to 8%. - Abstract: The power output of fusion devices is measured in terms of the neutron yield which relates directly to the fusion yield. JET made a transition from Carbon wall to ITER-Like Wall (Beryllium/Tungsten/Carbon) during 2010–11. Absolutely calibrated measurement of the neutron yield by JET neutron monitors was ensured by direct measurements using a calibrated {sup 252}Cf neutron source (NS) deployed by the in-vessel remote handling system (RHS) inside the JET vacuum vessel. Neutronic calculations were required in order to understand the neutron transport from the source in the vacuum vessel to the fission chamber detectors mounted outside the vessel on the transformer limbs of the tokamak. We developed a simplified computational model of JET and the JET RHS in Monte Carlo neutron transport code MCNP and analyzed the paths and structures through which neutrons reach the detectors and the effect of the JET RHS on the neutron monitor response. In addition we performed several sensitivity studies of the effect of substantial massive structures blocking the ports on the external neutron monitor response. As the simplified model provided a qualitative picture of the process only, some calculations were repeated using a more detailed full 3D model of the JET tokamak.

  8. Pedestal evolution physics in low triangularity JET tokamak discharges with ITER-like wall

    Science.gov (United States)

    Bowman, C.; Dickinson, D.; Horvath, L.; Lunniss, A. E.; Wilson, H. R.; Cziegler, I.; Frassinetti, L.; Gibson, K.; Kirk, A.; Lipschultz, B.; Maggi, C. F.; Roach, C. M.; Saarelma, S.; Snyder, P. B.; Thornton, A.; Wynn, A.; Contributors, JET

    2018-01-01

    The pressure gradient of the high confinement pedestal region at the edge of tokamak plasmas rapidly collapses during plasma eruptions called edge localised modes (ELMs), and then re-builds over a longer time scale before the next ELM. The physics that controls the evolution of the JET pedestal between ELMs is analysed for 1.4 MA, 1.7 T, low triangularity, δ  =  0.2, discharges with the ITER-like wall, finding that the pressure gradient typically tracks the ideal magneto-hydrodynamic ballooning limit, consistent with a role for the kinetic ballooning mode. Furthermore, the pedestal width is often influenced by the region of plasma that has second stability access to the ballooning mode, which can explain its sometimes complex evolution between ELMs. A local gyrokinetic analysis of a second stable flux surface reveals stability to kinetic ballooning modes; global effects are expected to provide a destabilising mechanism and need to be retained in such second stable situations. As well as an electron-scale electron temperature gradient mode, ion scale instabilities associated with this flux surface include an electro-magnetic trapped electron branch and two electrostatic branches propagating in the ion direction, one with high radial wavenumber. In these second stability situations, the ELM is triggered by a peeling-ballooning mode; otherwise the pedestal is somewhat below the peeling-ballooning mode marginal stability boundary at ELM onset. In this latter situation, there is evidence that higher frequency ELMs are paced by an oscillation in the plasma, causing a crash in the pedestal before the peeling-ballooning boundary is reached. A model is proposed in which the oscillation is associated with hot plasma filaments that are pushed out towards the plasma edge by a ballooning mode, draining their free energy into the cooler plasma there, and then relaxing back to repeat the process. The results suggest that avoiding the oscillation and maximising the region

  9. International tokamak reactor conceptual design overview

    International Nuclear Information System (INIS)

    Stacey, W.M. Jr.

    1983-01-01

    The International Tokamak Reactor (INTOR) Workshop is an unique collaborative effort among Euratom, Japan, the USA and the USSR, under the auspices of the IAEA, to assess, define, design, construct and operate the next major experiment in the World Tokamak Program beyond the TFTR, JET, JT-60, T-15 generation. During the Zero-Phase (1979), a technical data base assessment was performed, leading to a positive assessment of feasibility. During Phase-I (1/80-6/81), a conceptual design was developed to define the concept. The programmatic objectives are that INTOR should: (1) be the maximum reasonable step beyond the TFTR, JET, JT-60, T-15 generation of tokamaks, (2) demonstrate the plasma performance required for tokamak DEMOs, (3) test the development and integration into a reactor system of those technologies required for a DEMO, (4) serve as a test facility for blanket, tritium production, materials, and plasma engineering technology, (5) test fusion reactor component reliability, (6) test the maintainability of a fusion reactor, and (7) test the factors affecting the reliability, safety and environmental acceptability of a fusion reactor. A conceptual design has been developed to define a device which is consistent with these objectives. The design concept could, with a reasonable degree of confidence, be developed into a workable engineering design of a tokamak that met the performance objectives of INTOR. There is some margin in the design to allow for uncertainty. While design solutions have been found for all of the critical issues, the overall design may not yet be optimal. (author)

  10. An overview on plasma disruption mitigation and avoidance in tokamak

    International Nuclear Information System (INIS)

    He Kaihui; Pan Chuanhong; Feng Kaiming

    2002-01-01

    Plasma disruption, which seems to be unavoidable in Tokamak operation, occurs very fast and uncontrolled. In order to keep Tokamak plasma from disruption and mitigate the disruption frequency, the research on Tokamak plasma major disruption constitutes one of the main topics in plasma physics. The phenomena and processes of the precursor, thermal quench, current quench, VDE, halo current and runaway electrons generation during plasma disruption are analyzed in detail and systematically based on the data obtained from current Tokamaks such as TFTR, JET, JT-60U and ASDEX-U, etc. The methods to mitigate and avoid disruption in Tokamak are also highlighted schematically. Therefore, it is helpful and instructive for plasma disruption research in next generation large Tokamak such as ITER-FEAT

  11. TFTR/JET INTOR workshop on plasma transport tokamaks

    International Nuclear Information System (INIS)

    Singer, C.E.

    1985-01-01

    This report summarizes the proceedings of a Workshop on transport models for prediction and analysis of tokamak plasma confinement. Summaries of papers on theory, predictive modeling, and data analysis are included

  12. JET contributions to the workshop on the new phase for JET: the pumped divertor proposal

    International Nuclear Information System (INIS)

    1989-09-01

    Contributions to the Workshop consist of 13 papers on the new phase of operation of JET, including an outline of the objectives of the study of impurity control and the operating domain relative to the next generation of tokamaks. Studies are presented on the pumped divertor proposed for JET, diagnostic measurements required, and the performance expectations in the new configuration. (U.K.)

  13. Analysis of toroidal rotation data for the DIII-D tokamak

    International Nuclear Information System (INIS)

    John, H.St.; Burrell, K.H.; Groebner, R.; DeBoo, J.; Gohil, P.

    1989-01-01

    Both poloidal and toroidal rotation are observed during routine neutral beam heating operation of the DIII-D tokamak. Poloidal rotation results and the empirical techniques used to measure toroidal and poloidal rotation speeds are described by Groebner et al. Here we concentrate on the analysis of recent measurements of toroidal rotation made during diverted, H-mode operation of the DIII-D tokamak during co- and counter-neutral beam injection of hydrogen into deuterium plasmas. Similar studies have been previously reported for Doublet III, ASDEX, TFTR, JET and other tokamaks. (author) 13 refs., 4 figs

  14. From use cases of the Joint European Torus towards integrated commissioning requirements of the ITER tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Neto, A.C. [Fusion for Energy, 08019 Barcelona (Spain); Stephen, A. [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Sartori, F.; Cavinato, M. [Fusion for Energy, 08019 Barcelona (Spain); Farthing, J.W. [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Ranz, R.; Saibene, G. [Fusion for Energy, 08019 Barcelona (Spain); Winter, A. [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); Arnoux, G. [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Alves, D. [Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa (Portugal); Blackman, T.; Boboc, A.; Card, P.J.; Dalley, S.; Day, I.E. [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); De Tommasi, G. [Consorzio CREATE/Dipartimento di Ingegneria Elettrica e delle Tecnologie dell’Informazione, Università degli Studi di Napoli Federico II, Via Claudio 21, 80125 Napoli (Italy); Drewelow, P.; Elsmore, C.; Ivings, E.; Felton, R. [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); and others

    2015-10-15

    The Joint European Torus (JET) is the largest tokamak currently in operation in the world. One of the greatest challenges of JET is the integrated commissioning of all its major plant systems. This is driven, partially, by the size and complexity of its operational infrastructure and also by the fact that, being an international environment, it has to address the issues of integrating, commissioning and maintaining plant systems developed by third parties. The ITER tokamak, now in construction, is a fusion device twice the size of JET and, being a joint effort between the European Union, China, India, Japan, South Korea, the Russian Federation and the USA, it will share on a wider scale all of the JET challenges regarding integration and integrated commissioning of very large and complex plant systems. With the scope of taking advantage from the history and experience of JET, Fusion for Energy (F4E) has worked together with the Culham Centre for Fusion Energy (CCFE), the host and operator of JET, for the provision of ITER relevant user experiences related to the integrated commissioning of the tokamak. This work presents and discusses the main results and the methods that were used to extract and translate the commissioning experience information into ITER requirements.

  15. ICIT contribution to JET gamma-ray diagnostics enhancement

    International Nuclear Information System (INIS)

    Soare, S.; Curuia, M.; Zoita, V.

    2010-01-01

    Full text: Gamma-ray emission of tokamak plasmas is the result of the interaction of fast ions (fusion reaction products, including alpha particles, NBI ions, ICRH-accelerated ions) with main plasma impurities (e.g., carbon, beryllium). Gamma-ray diagnostics involve both gamma-ray imaging (cameras) and gamma-ray spectrometry (spectrometers). For the JET tokamak, gamma-ray diagnostics have been used to provide information on the characteristics of the fast ion population in plasmas. Two gamma-ray diagnostics enhancements project have been launched by JET and the MEdC/EURATOM Association has agreed to lead both of them with ICIT as projects leader. (authors)

  16. Liquid jets for fast plasma termination in tokamaks

    International Nuclear Information System (INIS)

    Rosenbluth, M.N.; Putvinskij, S.V.; Parks, P.B.

    1997-01-01

    Recent simulations by Putvisnkij et al. (PSI Conference, 1996) have shown that introducing impurities into the plasma in order to mitigate adverse disruption effects in ITER may actually be deleterious because of a potentially unwelcome phenomenon: generation of multi-MeV runaway electrons by the collisional avalanche mechanism (Rosenbluth, M.N., et al., in Fusion Energy 1996 (Proc. 16th Int. Conf. Montreal, 1996) Vol. 2, IAEA, Vienna (in press) Paper FP-26). The injection of a liquid hydrogen jet to deliver a massive density increase is proposed as a means of avoiding runaways, while providing the same beneficial effects as impurities. A discussion of many jet related topics, such as ablation/penetration, jet breakup time and stability, is presented. Owing to an ablation pressure instability, it is predicted that the jet will quickly break up into a regular chain of droplets with dimensions of approximately the size of the jet radius. It is found that while deep penetration in the plasma can easily be achieved, bubble growth and disruptive boiling (flashing) during the propagation in the vacuum gap between the nozzle exit and the plasma are the main processes limiting the jet survival time. Calculations indicate that for ITER reference parameters, the jet can remain coherent in vacuum for a distance ∼ 1 m before disintegrating. On the basis of this present understanding, the prospect for the safe termination of ITER discharges by high density liquid jet injection appears promising. (author). 20 refs, 6 figs, 3 tabs

  17. The JET project and the European fusion research programme

    International Nuclear Information System (INIS)

    Wuester, H.-O.

    1984-01-01

    The paper concerns the Joint European Torus (JET) project and the European Fusion Research Programme. Fusion as an energy source and commercial fusion power are briefly discussed. The main features of the JET apparatus and the tokamak magnetic field configuration are given. Also described are the specific aims of JET, and the proposed future fusion reactor programme. (U.K.)

  18. Detritiation of tiles from tokamaks by laser cleaning

    International Nuclear Information System (INIS)

    Coad, J. Paul; Widdowson, Anna; Farcage, Daniel; Semerok, Alexander; Thro, P.-Y.; Likonen, Jari; Renvall, Tommi

    2007-01-01

    Laser ablation has been used to clean surfaces or to decontaminate hot cells by removing paint, and has been tested on deposited carbon layers from the TEXTOR tokamak. This paper reports on successful trials in the Beryllium Handling Facility of a pulsed laser cleaning system to remove H-isotope containing carbon deposits on tiles from the JET tokamak. The laser beam is rastered over the surface of the tiles to remove the deposit. Two types of JET carbon-fibre composite (CFC) tiles were treated. The first was covered with carbon-based deposits up to 300 μm thick with high H-isotope content, the other was covered with a mixed Be/C film ∼ 50 microns thick. One scan of the laser was sufficient to completely change the appearance and expose the fibre planes. From cross-sectional micrographs, it was found that overall three scans provided the most effective settings for complete film removal. An area 250 cm 2 of the second tile was cleaned in 20 minutes, clearly demonstrating the efficiency of laser cleaning for the removal of tokamak deposits such as likely to occur in ITER. (authors)

  19. A generic access to shot-based data for European Tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Signoret, J.; Imbeaux, F. [Association EURATOM-CEA, CEA / DSM / Institut de Recherche sur la Fusion par confinement Magnetique, CEA-Cadarache, 13 - ST-Paul-Lez-Durance (France)

    2009-07-01

    The EFDA Integrated Tokamak Modeling Task Force has defined a data structure offering a generic representation of the properties of physics problems and tokamak subsystem characteristics. It gathers the hardware description, modeling results and data measured during experiments, structured in terms of Consistent Physical Objects (CPOs). A generic tool has been developed to retrieve shot-based data from the various European tokamak databases: Exp2ITM. A tokamak specific XML 'mapping file' is used to map the local data formats to the ITM (Integrated Tokamak Modeling) data format. Exp2ITM is then dynamically generated from the ITM data structure and uses generic procedures to import the shot-based data. Successful tests show we have managed to import into the ITM DB experimental data from Jet and Tore-Supra. This document is a poster. (authors)

  20. Core transport properties in JT-60U and JET identity plasmas

    NARCIS (Netherlands)

    Litaudon, X.; Sakamoto, Y.; de Vries, P. C.; Salmi, A.; Tala, T.; Angioni, C.; Benkadda, S.; Beurskens, M. N. A.; Bourdelle, C.; Brix, M.; Crombe, K.; Fujita, T.; Futatani, S.; Garbet, X.; Giroud, C.; Hawkes, N. C.; Hayashi, N.; Hoang, G. T.; Hogeweij, G. M. D.; Matsunaga, G.; Nakano, T.; Oyama, N.; Parail, V.; Shinohara, K.; Suzuki, T.; Takechi, M.; Takenaga, H.; Takizuka, T.; Urano, H.; Voitsekhovitch, I.; Yoshida, M.

    2011-01-01

    The paper compares the transport properties of a set of dimensionless identity experiments performed between JET and JT-60U in the advanced tokamak regime with internal transport barrier, ITB. These International Tokamak Physics Activity, ITPA, joint experiments were carried out with the same plasma

  1. Jet Joint Undertaking. Vol. 2

    International Nuclear Information System (INIS)

    1989-06-01

    The scientific, technical, experimental and theoretical investigations related to JET tokamak are presented. The JET Joint Undertaking, Volume 2, includes papers presented at: the 15th European Conference on controlled fusion and plasma heating, the 15th Symposium on fusion technology, the 12th IAEA Conference on plasma physics and controlled nuclear fusion research, the 8th Topical Meeting on technology of fusion. Moreover, the following topics, concerning JET, are discussed: experience with wall materials, plasma performance, high power ion cyclotron resonance heating, plasma boundary, results and prospects for fusion, preparation for D-T operation, active gas handling system and remote handling equipment

  2. A simultaneous description of fast wave e-TTMP and ion current drive effects on shear in a tokamak: theory and experiments in JET

    International Nuclear Information System (INIS)

    Bhatnagar, V.P.; Bosia, G.; Jacquinot, J.; Porcelli, F.

    1993-01-01

    A controlled local modification of the plasma-current profile, the safety factor q or shear (dq/dr) in a tokamak can lead to an improvement in its performance. For example, enhanced confinement in JET discharges with deep pellet injection is found to be associated with a reversal of the shear. Also, a significant control over the sawteeth behaviour in the JET tokamak has been found to occur when the shear at the q = 1 surface is modified by a dipolar-current driven by ICRF in the minority-ion heating regime. This could give a handle on the ejection of fast particles and hence on burn control in a reactor. The above sawtooth control may also be used to ease the ash removal in a reactor. When an ICRH antenna array is phased (Δφ ≠ 0 or π), the excited asymmetric k // -spectrum can drive non inductive currents by interaction of waves both with electrons (TTMP and e-Landau damping) and ions at minority (fundamental) or harmonic cyclotron resonances depending upon the scenario. Therefore, in any modeling of ICRF current drive, both (electron and ion) current drive mechanisms must be included simultaneously to correctly represent the non inductive current drive profile. To devise scenarios of shear control by minority current drive, that take advantage of the inherent electron current drive as well, we have developed a model based on earlier theories to calculate, for the first time, the two effects simultaneously. (author) 11 refs., 5 figs

  3. JET and COMPASS asymmetrical disruptions

    Czech Academy of Sciences Publication Activity Database

    Gerasimov, S.N.; Abreu, P.; Baruzzo, M.; Drozdov, V.; Dvornova, A.; Havlíček, Josef; Hender, T.C.; Hronová-Bilyková, Olena; Kruezi, U.; Li, X.; Markovič, Tomáš; Pánek, Radomír; Rubinacci, G.; Tsalas, M.; Ventre, S.; Villone, F.; Zakharov, L.E.

    2015-01-01

    Roč. 55, č. 11 (2015), s. 113006-113006 ISSN 0029-5515 R&D Projects: GA MŠk(CZ) LM2011021 Institutional support: RVO:61389021 Keywords : tokamak * asymmetrical disruption * JET * COMPASS Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 4.040, year: 2015

  4. Tokamaks (Second Edition)

    Energy Technology Data Exchange (ETDEWEB)

    Stott, Peter [JET, UK (United Kingdom)

    1998-10-01

    The first edition of John Wesson's book on tokamaks, published in 1987, established itself as essential reading for researchers in the field of magnetic confinement fusion: it was an excellent introduction for students to tokamak physics and also a valuable reference work for the more experienced. The second edition, published in 1997, has been completely rewritten and substantially enlarged (680 pages compared with 300). The new edition maintains the aim of providing a simple introduction to basic tokamak physics, but also includes discussion of the substantial advances in fusion research during the past decade. The new book, like its predecessor, is well written and commendable for its clarity and accuracy. In fact many of the chapters are written by a series of co-authors bringing the benefits of a wide range of expertise but, by careful editing, Wesson has maintained a uniformity of style and presentation. The chapter headings and coverage for the most part remain the same - but are expanded considerably and brought up to date. The most substantial change is that the single concluding chapter in the first edition on 'Experiments' has been replaced by three chapters: 'Tokamak experiments' which deals with some of the earlier key experiments plus a selection of recent small and medium-sized devices, 'Large experiments' which gives an excellent summary of the main results from the four large tokamaks - TFTR, JET, JT60/JT60U and DIII-D, and 'The future' which gives a very short (possibly too short in my opinion) account of reactors and ITER. This is an excellent book, which I strongly recommend should have a place - on the desk rather than in the bookshelf - of researchers in magnetic confinement fusion. (book review)

  5. Tokamaks (Second Edition)

    International Nuclear Information System (INIS)

    Stott, Peter

    1998-01-01

    The first edition of John Wesson's book on tokamaks, published in 1987, established itself as essential reading for researchers in the field of magnetic confinement fusion: it was an excellent introduction for students to tokamak physics and also a valuable reference work for the more experienced. The second edition, published in 1997, has been completely rewritten and substantially enlarged (680 pages compared with 300). The new edition maintains the aim of providing a simple introduction to basic tokamak physics, but also includes discussion of the substantial advances in fusion research during the past decade. The new book, like its predecessor, is well written and commendable for its clarity and accuracy. In fact many of the chapters are written by a series of co-authors bringing the benefits of a wide range of expertise but, by careful editing, Wesson has maintained a uniformity of style and presentation. The chapter headings and coverage for the most part remain the same - but are expanded considerably and brought up to date. The most substantial change is that the single concluding chapter in the first edition on 'Experiments' has been replaced by three chapters: 'Tokamak experiments' which deals with some of the earlier key experiments plus a selection of recent small and medium-sized devices, 'Large experiments' which gives an excellent summary of the main results from the four large tokamaks - TFTR, JET, JT60/JT60U and DIII-D, and 'The future' which gives a very short (possibly too short in my opinion) account of reactors and ITER. This is an excellent book, which I strongly recommend should have a place - on the desk rather than in the bookshelf - of researchers in magnetic confinement fusion. (book review)

  6. Magnetic confinement experiment. I: Tokamaks

    International Nuclear Information System (INIS)

    Goldston, R.J.

    1995-08-01

    Reports were presented at this conference of important advances in all the key areas of experimental tokamak physics: Core Plasma Physics, Divertor and Edge Physics, Heating and Current Drive, and Tokamak Concept Optimization. In the area of Core Plasma Physics, the biggest news was certainly the production of 9.2 MW of fusion power in the Tokamak Fusion Test Reactor, and the observation of unexpectedly favorable performance in DT plasmas. There were also very important advances in the performance of ELM-free H- (and VH-) mode plasmas and in quasi-steady-state ELM'y operation in JT-60U, JET, and DIII-D. In all three devices ELM-free H-modes achieved nTτ's ∼ 2.5x greater than ELM'ing H-modes, but had not been sustained in quasi-steady-state. Important progress has been made on the understanding of the physical mechanism of the H-mode in DIII-D, and on the operating range in density for the H-mode in Compass and other devices

  7. Plasma diagnostics on large tokamaks

    International Nuclear Information System (INIS)

    Orlinskij, D.V.; Magyar, G.

    1988-01-01

    The main tasks of the large tokamaks which are under construction (T-15 and Tore Supra) and of those which have already been built (TFTR, JET, JT-60 and DIII-D) together with their design features which are relevant to plasma diagnostics are briefly discussed. The structural features and principal characteristics of the diagnostic systems being developed or already being used on these devices are also examined. The different diagnostic methods are described according to the physical quantities to be measured: electric and magnetic diagnostics, measurements of electron density, electron temperature, the ion components of the plasma, radiation loss measurements, spectroscopy of impurities, edge diagnostics and study of plasma stability. The main parameters of the various diagnostic systems used on the six large tokamaks are summarized in tables. (author). 351 refs, 44 figs, 22 tabs

  8. Recent results on confinement in JET

    International Nuclear Information System (INIS)

    Campbell, D.J.

    1992-01-01

    The JET device is the world's largest tokamak and has been utilized in plasma heating experiments at total powers of up to 35MW using both neutral beam injection (NBI) and ion cyclotron resonance heating (ICRH). At the highest performance, JET plasmas have achieved conditions equivalent to energy ''breakeven''. A principal aim of the JET experiment is the investigation of plasma heating and confinement in plasma regimes relevant to thermonuclear ignition. The central issues in confinement physics involved in these advances are briefly reviewed and the most recent investigations of transport in high performance plasmas are summarized. (Author)

  9. Fabrication of microlens array with controllable high NA and tailored optical characteristics using confined ink-jetting

    Science.gov (United States)

    Wang, Li; Luo, Yu; Liu, ZengZeng; Feng, Xueming; Lu, Bingheng

    2018-06-01

    This work presents an economic and controllable fabricating method of high numerical aperture (NA) polymer microlens array (MLA) based on ink-jetting technology. The MLAs are ink-jetted to align on micro platforms patterned flexible PDMS substrate. The shape of a sole lens is constructed by the ink-jetted pre-cured polymer volume confined on a micro platform. In this way, MLAs with targeted geometries-as well as tailored optical characteristics-can be printed, leading to freely designed optical properties. High NA from 0.446 to 0.885 and focal lengths between 99.26 μm and 39.45 μm are demonstrated, confirming theoretical predictions. Particularly, both the simulations and experimental measurements in optical properties are carried out, demonstrating that microlenses with shapes beyond a hemisphere (CA > 90°) exhibits higher light utilization efficiency and wider viewing angle. Meanwhile, the MLAs are fabricated on flexible PDMS substrates and can be attached to other curved surfaces for wider field of view imaging and higher sensitivity.

  10. Identification of minority ion cyclotron emission during radio frequency heating in the JET tokamak

    International Nuclear Information System (INIS)

    Cottrell, G.A.

    1999-11-01

    First measurements and identification of Minority Ion Cyclotron Emission (MICE) during ICRF (H)D minority heating in the JET tokamak are presented. An inner wall radiofrequency (rf) probe shows the new single MICE spectral line, downshifted from the heating, frequency and appearing ∼ 400 ms after the ICRH switch-on. The line is narrow (Δω / ω) ∼ 0.04), characterised by the ion cyclotron frequency of minority protons in the outer edge mid-plane plasma and is observed irrespective of whether single or multi-frequency ICRH is applied. Threshold conditions for MICE are: coupled RF power to the plasma P rf ≥ 4.5 MW; total fast ion energy content W fast ≥ 0.6 MJ. At the time of the rapid switch-on of MICE, the measured power loss from the energetic minority ions is ∼ 0.1 ± 0.1 MW, constituting rf . The observations are consistent with the classical evolution and population of the plasma edge with ∼ 3 MeV ICRH protons on orbits near the outboard limiters. Particle loss and energy filtering contribute to a local non-Maxwellian energetic ion distribution which is susceptible to ion cyclotron instability

  11. Multi-megajoule heating of large tokamaks with high energy heavy ion beams

    International Nuclear Information System (INIS)

    Dei-Cas, R.

    1981-07-01

    The fast neutral injection heating and RF heating for tokamak like plasmas are now well established. We consider in this paper the use of high energy (approximately 1 GeV) heavy ions (Xe 132 ) to reach ignition in JET or INTOR like tokamaks. The main advantages of such a method will be outlined. The capture and the confinement of heavy ions have been analysed in a particular case and with the described RF linac it seems possible to inject in the order of 50 MJ in 1 sec with a modest increase of the effective charge Zsub(eff)<1.05 in a JET-like plasma for a particle life time of 1 sec and then the additional radiated power should be maintained at a relatively low level in comparison to the injected power

  12. Analysis of a global energy confinement database for JET ohmic plasmas

    International Nuclear Information System (INIS)

    Bracco, G.; Thomsen, K.

    1997-01-01

    A database containing global energy confinement data for JET ohmic plasmas in the campaigns from 1984 to 1992 has been established. An analysis is presented of this database and the results are compared with data from other tokamaks, such as the Axially Symmetric Divertor Experiment (ASDEX), Frascati Tokamak Upgrade (FTU) and Tore Supra. The trends of JET ohmic confinement appear to be similar to those observed on other tokamaks: a linear dependence of the global energy confinement time on density is observed up to a density value where a saturation is attained; this density value defines the border between the linear and the saturated ohmic confinement regimes; this border is shifted towards higher density values if the q value of the discharge is decreased; the global confinement time in the saturated ohmic regime increases less than linearly with the value of the magnetic field. (author). 20 refs, 13 figs, 4 tabs

  13. Pneumatic pellet injector for JET

    International Nuclear Information System (INIS)

    Andelfinger, C.; Buechl, K.; Jacobi, D.; Sandmann, W.; Schiedeck, J.; Schilling, H.B.; Weber, G.

    1983-07-01

    Pellet injection is a useful tool for plasma diagnostics of tokamaks. Pellets can be applied for investigation of particle, energy and impurity transport, fueling efficiency and magnetic surfaces. Design, operation and control of a single shot pneumatic pellet gun is described in detail including all supplies, the vacuum system and the diagnostics of the pellet. The arrangement of this injector in the torus hall and the interfaces to the JET system and CODAS are considered. A guide tube system for pellet injection is discussed but it will not be recommended for JET. (orig.)

  14. The experience with JET's combined dc/Rf glow discharge cleaning (GDC) system

    International Nuclear Information System (INIS)

    Pearce, R.J.H.; Andrew, P.; Bryan, S.

    1996-01-01

    The JET Tokamak was fitted with four new electrodes of novel design, each powered from individual computer controlled dc and RF supplies. Details of enhancements and problems from 15 months experience with the system are outlined. Experiments were performed to assess the effect of RF on the glow discharge characteristics, and to establish stable glow at low pressure and high voltage. JET combined RF/dc glow discharge cleaning (GDC) had no significant advantages over pure dc GDC, provided highly stable dc current control was obtained. In fact, the mechanically weak electrode inductor spiral required to allow RF posed a distinct disadvantage. The electrodes were converted to simple plates, following damage caused by halo currents during Tokamak plasma disruptions. The performance of these electrodes was assessed. Future developments in the JET GDC system are outlined. (Author)

  15. Mode particle resonances during near-tangential neutral beam injection in large tokamaks

    International Nuclear Information System (INIS)

    Kaita, R.; White, R.B.; Morris, A.W.; Fredrickson, E.D.; McGuire, K.M.; Medley, S.S.; Scott, S.D.

    1988-01-01

    Coherent magnetohydrodynamic modes have been observed during neutral beam injection in TFTR and JET. Periodic bursts of oscillations were detected with several plasma diagnostics, and Fokker-Planck calculations show that the populations of trapped particles in both tokamaks are sufficient to account for fishbone destabilization. Estimates of mode parameters are in reasonable agreement with the experiments, and they indicate that the fishbone mode may continue to affect the performance of intensely heated tokamaks. 13 refs., 1 fig., 1 tab

  16. Sub-millisecond electron density profile measurement at the JET tokamak with the fast lithium beam emission spectroscopy system

    Science.gov (United States)

    Réfy, D. I.; Brix, M.; Gomes, R.; Tál, B.; Zoletnik, S.; Dunai, D.; Kocsis, G.; Kálvin, S.; Szabolics, T.; JET Contributors

    2018-04-01

    Diagnostic alkali atom (e.g., lithium) beams are routinely used to diagnose magnetically confined plasmas, namely, to measure the plasma electron density profile in the edge and the scrape off layer region. A light splitting optics system was installed into the observation system of the lithium beam emission spectroscopy diagnostic at the Joint European Torus (JET) tokamak, which allows simultaneous measurement of the beam light emission with a spectrometer and a fast avalanche photodiode (APD) camera. The spectrometer measurement allows density profile reconstruction with ˜10 ms time resolution, absolute position calculation from the Doppler shift, spectral background subtraction as well as relative intensity calibration of the channels for each discharge. The APD system is capable of measuring light intensities on the microsecond time scale. However ˜100 μs integration is needed to have an acceptable signal to noise ratio due to moderate light levels. Fast modulation of the beam up to 30 kHz is implemented which allows background subtraction on the 100 μs time scale. The measurement covers the 0.9 background subtraction, the relative calibration, and the comprehensive error calculation, runs a Bayesian density reconstruction code, and loads results to the JET database. The paper demonstrates the capability of the APD system by analyzing fast phenomena like pellet injection and edge localized modes.

  17. Electrical testing and performance evaluation of 1:1 prototype JET ELM control coils

    Energy Technology Data Exchange (ETDEWEB)

    Kanabar, Deven, E-mail: deven@ipr.res.in; Roy, Swati; Ghate, Mahesh; Raj, Piyush; Kundu, Ananya; Kumar, Nitish; Bhavsar, Dhaval; Panchal, Arun; Pradhan, Subrata, E-mail: pradhan@ipr.res.in

    2016-12-15

    Highlights: • An appropriate 1:1 prototype Small and Large ELM coils for JET have been successfully manufactured using indigenous technologies. • ELM coils have been tested extensively to verify and validated their performance with respect to operational requirement of JET. • The test results confirm and validate the electrical performance of ELM coils. - Abstract: Magnet Technology Development Division at Institute for Plasma research is engaged in extensive R & D for appropriate technologies towards manufacturing of Edge Localized Mode (ELM) magnets for Large Tokamak such as Joint European Torus (JET) as well as for Steady State Superconducting Tokamak (SST-1). Under this project, manufacturing of 1:1 prototype of Large and Small JET ELM control coils (CC) is completed incorporating indigenously developed manufacturing and insulation technologies. Performance evaluation of both the types of coil has been completed for its current carrying capability and insulation resistance as required by various operational scenarios of JET. Experimental setups, test procedures and measurements for electrical characterization of both type of ELM control coil has been discussed in this paper.

  18. Electrical testing and performance evaluation of 1:1 prototype JET ELM control coils

    International Nuclear Information System (INIS)

    Kanabar, Deven; Roy, Swati; Ghate, Mahesh; Raj, Piyush; Kundu, Ananya; Kumar, Nitish; Bhavsar, Dhaval; Panchal, Arun; Pradhan, Subrata

    2016-01-01

    Highlights: • An appropriate 1:1 prototype Small and Large ELM coils for JET have been successfully manufactured using indigenous technologies. • ELM coils have been tested extensively to verify and validated their performance with respect to operational requirement of JET. • The test results confirm and validate the electrical performance of ELM coils. - Abstract: Magnet Technology Development Division at Institute for Plasma research is engaged in extensive R & D for appropriate technologies towards manufacturing of Edge Localized Mode (ELM) magnets for Large Tokamak such as Joint European Torus (JET) as well as for Steady State Superconducting Tokamak (SST-1). Under this project, manufacturing of 1:1 prototype of Large and Small JET ELM control coils (CC) is completed incorporating indigenously developed manufacturing and insulation technologies. Performance evaluation of both the types of coil has been completed for its current carrying capability and insulation resistance as required by various operational scenarios of JET. Experimental setups, test procedures and measurements for electrical characterization of both type of ELM control coil has been discussed in this paper.

  19. Theory of energetic/alpha particle effects on magnetohydrodynamic modes in tokamaks

    International Nuclear Information System (INIS)

    Chen, L.; White, R.B.; Rewoldt, G.; Colestock, P.; Rutherford, P.H.; Chen, Y.P.; Ke, F.J.; Tsai, S.T.; Bussac, M.N.

    1989-01-01

    The presence of energetic particles is shown to qualitatively modify the stability properties of ideal as well as resistive magnetohydrodynamic (MHD) modes in tokamaks. Specifically, we demonstrate that, consistent with highpower ICRF heating experiments in JET, high energy trapped particles can effectively stabilize the sawtooth mode, providing a possible route to stable high current tokamak operation. An alternative stabilization scheme employing barely circulating energetic particles is also proposed. Finally, we present analytical and numerical studies on the excitations of high-n MHD modes via transit resonances with circulating alpha particles. 14 refs., 3 figs

  20. Statistical analysis of JET disruptions

    International Nuclear Information System (INIS)

    Tanga, A.; Johnson, M.F.

    1991-07-01

    In the operation of JET and of any tokamak many discharges are terminated by a major disruption. The disruptive termination of a discharge is usually an unwanted event which may cause damage to the structure of the vessel. In a reactor disruptions are potentially a very serious problem, hence the importance of studying them and devising methods to avoid disruptions. Statistical information has been collected about the disruptions which have occurred at JET over a long span of operations. The analysis is focused on the operational aspects of the disruptions rather than on the underlining physics. (Author)

  1. Studies of Be migration in the JET tokamak using AMS with 10Be marker

    Science.gov (United States)

    Bykov, I.; Bergsåker, H.; Possnert, G.; Zhou, Y.; Heinola, K.; Pettersson, J.; Conroy, S.; Likonen, J.; Petersson, P.; Widdowson, A.

    2016-03-01

    The JET tokamak is operated with beryllium limiter tiles in the main chamber and tungsten coated carbon fiber composite tiles and solid W tiles in the divertor. One important issue is how wall materials are migrating during plasma operation. To study beryllium redistribution in the main chamber and in the divertor, a 10Be enriched limiter tile was installed prior to plasma operations in 2011-2012. Methods to take surface samples have been developed, an abrasive method for bulk Be tiles in the main chamber, which permits reuse of the tiles, and leaching with hot HCl to remove all Be deposited at W coated surfaces in the divertor. Quantitative analysis of the total amount of Be in cm2 sized samples was made with inductively coupled plasma atomic emission spectroscopy (ICP-AES). The 10Be/9Be ratio in the samples was measured with accelerator mass spectrometry (AMS). The experimental setup and methods are described in detail, including sample preparation, measures to eliminate contributions in AMS from the 10B isobar, possible activation due to plasma generated neutrons and effects of diffusive isotope mixing. For the first time marker concentrations are measured in the divertor deposits. They are in the range 0.4-1.2% of the source concentration, with moderate poloidal variation.

  2. Task III: auxillary heating in tokamaks and tandem mirrors. Progress report on fusion plasma theory

    International Nuclear Information System (INIS)

    Scharer, J.E.

    1986-06-01

    The research we have accomplished with this grant has focused on ICRF coupling, wave propagation, heating and breakeven studies for tokamaks such as JET. The highlights include fundamental work on a differential equation for wave fields incorporating equilibrium gradients, strong absorption and mode conversion and a new wave power absorption and conservation relation for ICRF in inhomogeneous plasmas. We have also formulated and developed a code which solves differential equation for ICRF waveguide coupling in tokamak edge density regions. We are also examining the excitation of ion Bernstein waves from fast magnetosonic waves occurring in density gradients. Our current efforts involve the explanation of current JET ICRF results such as the large electron sawteeth in the core region in terms of hot, non-Maxwellian ICRF theory

  3. JET Joint Undertaking

    International Nuclear Information System (INIS)

    Keen, B.E.

    1986-03-01

    This is an overview summary of the scientific and technical advances at JET during the year 1985, supplemented by appendices of detailed contributions (in preprint form) of eight of the more important JET articles produced during that year. It is aimed not only at specialists and experts but also at a more general scientific community. Thus there is a brief summary of the background to the project, a description of the basic objectives of JET and the principle design features of the machine. The new structure of the Project Team is also explained. Developments and future plans are included. Improvements considered are those which are designed to overcome certain limitations encountered generally on Tokamaks, particularly those concerned with density limits, with plasma MHD behaviour, with impurities and with plasma transport. There is also a complete list of articles, reports and conference papers published in 1985 - there are 167 such items listed. (UK)

  4. Efficiency of an on-line isotope separator system employing cooled and NaCl-loaded He-jet methods

    International Nuclear Information System (INIS)

    Aeystoe, J.; Rantala, V.; Valli, K.; Hillebrand, S.; Kortelahti, M.; Eskola, K.; Raunemaa, T.

    1976-01-01

    A pure helium-jet at liquid nitrogen temperature coupled to a Nielsen type ion source, and a NaCl-loaded helium-jet coupled to a hollow-cathode ion source have been investigated as means to connect a cyclotron target chamber on-line to a mass separator. Technical details and performances of some critical parts of the system are described. Total separation efficiencies measured under various experimental conditions for several nuclides vary between 0.01 and 1.0%. (Auth.)

  5. A programmatic framework for the Tokamak Physics Experiment (TPX)

    International Nuclear Information System (INIS)

    Thomassen, K.I.; Goldston, R.J.; Neilson, G.H.

    1993-01-01

    Significant advances have been made in the confinement of reactor-grade plasmas, so that the authors are now preparing for experiments at the open-quotes power breakevenclose quotes level in the JET and TFTR experiments. In ITER the authors will extend the performance of tokamaks into the burning plasma regime, develop the technology of fusion reactors, and produce over a gigawatt of fusion power. Besides taking these crucial steps toward the technical feasibility of fusion, the authors must also take steps to ensure its economic acceptability. The broad requirements for economically attractive tokamak reactors based on physics advancements have been set forth in a number of studies. An advanced physics data base is emerging from a physics program of concept improvement using existing tokamaks around the world. This concept improvements program is emerging as the primary focus of the US domestic tokamak program, and a key element of that program is the proposed Tokamak Physics Experiment (TPX). With TPX the authors can develop the scientific data base for compact, continuously-operating fusion reactors, using advanced steady-state control techniques to improve plasma performance. The authors can develop operating techniques needed to ensure the success of ITER and provide first-time experience with several key fusion reactor technologies. This paper explains the relationships of TPX to the current US fusion physics program, to the ITER program, and to the development of an attractive tokamak demonstration plant for this next stage in the fusion program

  6. The LIDAR Thomson Scattering Diagnostic on JET

    DEFF Research Database (Denmark)

    Salzmann, H.; Bundgaard, J.; Gadd, A.

    1988-01-01

    By combining the time‐of‐flight or LIDAR principle with a Thomson backscatter diagnostic, spatial profiles of the electron temperature and density are measured in a magnetically confined fusion plasma. This technique was realized for the first time on the JET tokamak. A ruby laser (3‐J pulse ener...

  7. Measurement of the effective plasma ion mass in large tokamaks

    International Nuclear Information System (INIS)

    Lister, J.B.; Villard, L.; Ridder, G. de

    1997-01-01

    There is not yet a straightforward method for the measurement of the D-T ratio in the centre of a tokamak plasma. One of the simpler measurements put forward in the past is the interpretation of the MHD spectrum in the frequency range of the Global Alfven Eigenmodes (GAE). However, the frequencies of these modes do not only depend on the plasma mass, but are also quite strongly dependent on the details of the current and density profiles, creating a problem of deconvolution of the estimate of the plasma mass from an implicit relationship between several measurable plasma parameters and the detected eigenmode frequencies. This method has been revised to assess its likely precision for the JET tokamak. The low n GAE modes are sometimes too close to the continuum edge to be detectable and the interpretation of the GAE spectrum is rendered less direct than had been hoped. We present a statistical study on the precision with which the D-T ratio could be estimated from the GAE spectrum on JET. (author) 4 figs., 8 refs

  8. Progress in Neutron Diagnostics at JET

    Czech Academy of Sciences Publication Activity Database

    Mlynář, Jan; Bonheure, G.; Murari, A.; Bertalot, L.; Angelone, M.; Pillon, M.; Conroy, S.; Ericsson, G.; Kaellne, J.; Popovichev, S.

    2006-01-01

    Roč. 56, suppl.B (2006), B118-B124 ISSN 0011-4626. [Symposium on Plasma Physics and Technology /22nd./. Praha, 26.6.2006-29.6.2006] Institutional research plan: CEZ:AV0Z20430508 Keywords : tokamak * JET * fusion * neutrons diagnostics Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.568, year: 2006

  9. Comparison of runaway electron generation parameters in small, medium-sized and large tokamaks—A survey of experiments in COMPASS, TCV, ASDEX-Upgrade and JET

    Science.gov (United States)

    Plyusnin, V. V.; Reux, C.; Kiptily, V. G.; Pautasso, G.; Decker, J.; Papp, G.; Kallenbach, A.; Weinzettl, V.; Mlynar, J.; Coda, S.; Riccardo, V.; Lomas, P.; Jachmich, S.; Shevelev, A. E.; Alper, B.; Khilkevitch, E.; Martin, Y.; Dux, R.; Fuchs, C.; Duval, B.; Brix, M.; Tardini, G.; Maraschek, M.; Treutterer, W.; Giannone, L.; Mlynek, A.; Ficker, O.; Martin, P.; Gerasimov, S.; Potzel, S.; Paprok, R.; McCarthy, P. J.; Imrisek, M.; Boboc, A.; Lackner, K.; Fernandes, A.; Havlicek, J.; Giacomelli, L.; Vlainic, M.; Nocente, M.; Kruezi, U.; COMPASS Team; TCV Team; ASDEX-Upgrade Team; EUROFusion MST1 Team; contributors, JET

    2018-01-01

    This paper presents a survey of the experiments on runaway electrons (RE) carried out recently in frames of EUROFusion Consortium in different tokamaks: COMPASS, ASDEX-Upgrade, TCV and JET. Massive gas injection (MGI) has been used in different scenarios for RE generation in small and medium-sized tokamaks to elaborate the most efficient and reliable ones for future RE experiments. New data on RE generated at disruptions in COMPASS and ASDEX-Upgrade was collected and added to the JET database. Different accessible parameters of disruptions, such as current quench rate, conversion rate of plasma current into runaways, etc have been analysed for each tokamak and compared to JET data. It was shown, that tokamaks with larger geometrical sizes provide the wider limits for spatial and temporal variation of plasma parameters during disruptions, thus extending the parameter space for RE generation. The second part of experiments was dedicated to study of RE generation in stationary discharges in COMPASS, TCV and JET. Injection of Ne/Ar have been used to mock-up the JET MGI runaway suppression experiments. Secondary RE avalanching was identified and quantified for the first time in the TCV tokamak in RE generating discharges after massive Ne injection. Simulations of the primary RE generation and secondary avalanching dynamics in stationary discharges has demonstrated that RE current fraction created via avalanching could achieve up to 70-75% of the total plasma current in TCV. Relaxations which are reminiscent the phenomena associated to the kinetic instability driven by RE have been detected in RE discharges in TCV. Macroscopic parameters of RE dominating discharges in TCV before and after onset of the instability fit well to the empirical instability criterion, which was established in the early tokamaks and examined by results of recent numerical simulations.

  10. First experiments in JET

    International Nuclear Information System (INIS)

    Rebut, P.H.; Bartlett, D.V.; Baeumel, G.

    1985-01-01

    Results obtained from JET since June 1983 are described which show that this large tokamak behaves in a similar manner to smaller tokamaks, but with correspondingly improved plasma parameters. Long-duration hydrogen and deuterium plasmas (>10 s) have been obtained with electron temperatures reaching >4 keV for power dissipations =1.6), loss of vertical stability occurred, as expected from previous calculations. Forces of several hundred tonnes (at Isub(p)=2.7 MA) were transmitted to the vacuum vessel. Measured confinement times are larger than the corresponding INTOR values. The maximum achievable density is limited by disruptions. Impurity levels determine this limiting density, and the paper concludes with proposals to reduce these. In addition, progress in neutral injection and RF heating is described, as well as preparations for D-T operation. (author)

  11. Particle transport in JET and TCV-H mode plasmas

    International Nuclear Information System (INIS)

    Maslov, M.

    2009-10-01

    Understanding particle transport physics is of great importance for magnetically confined plasma devices and for the development of thermonuclear fusion power for energy production. From the beginnings of fusion research, more than half a century ago, the problem of heat transport in tokamaks attracted the attention of researchers, but the particle transport phenomena were largely neglected until fairly recently. As tokamak physics advanced to its present level, the physics community realized that there are many hurdles to the development of fusion power beyond the energy confinement. Particle transport is one of the outstanding issues. The aim of this thesis work is to study the anomalous (turbulence driven) particle transport in tokamaks on the basis of experiments on two different devices: JET (Joint European Torus) and TCV (Tokamak à Configuration Variable). In particular the physics of particle inward convection (pinch), which causes formation of peaked density profiles, is addressed in this work. Density profile peaking has a direct, favorable effect on fusion power in a reactor, we therefore also propose an extrapolation to the international experimental reactor ITER, which is currently under construction. To complete the thesis research, a comprehensive experimental database was created on the basis of data collected on JET and TCV during the duration of the thesis. Improvements of the density profile measurements techniques and careful analysis of the experimental data allowed us to derive the dependencies of density profile shape on the relevant plasma parameters. These improved techniques also allowed us to dispel any doubts that had been voiced about previous results. The major conclusions from previous work on JET and other tokamaks were generally confirmed, with some minor supplements. The main novelty of the thesis resides in systematic tests of the predictions of linear gyrokinetic simulations of the ITG (Ion Temperature Gradient) mode against the

  12. The energy principle applied to diverted tokamak configurations

    International Nuclear Information System (INIS)

    Atanasiu, C. V.; Guenter, S.; Lackner, K.; Moraru, A.; Zakharov, L. E.; Subbotin, A. A.

    2008-01-01

    Writing the expression of the potential energy in terms of the perturbation of the flux function, and performing an Euler minimisation, one obtains a system of ordinary differential equations in that perturbation. For a diverted configuration, the usual vanishing boundary conditions for the perturbed flux function at the magnetic axis and at infinity can no longer be used. In place of the vanishing boundary conditions at infinity, an approach to fix 'natural' boundary conditions for the system of differential equations for the perturbed flux function, just at the plasma boundary has been developed. As an example of application of our approaches, a particular equilibrium configuration of the ASDEX Upgrade tokamak has been considered and a detailed investigation of the dependence of the tearing stability parameter Δ' on plasma shape is given for a realistic tokamak equilibrium. The results shown are at least in qualitative agreement with experimental observations on ASDEX Upgrade and JET of a stabilizing influence of triangularity. The knowledge of Δ' for realistic tokamak plasmas is especially important for understanding of the plasma stability against NTMs. (authors)

  13. Runaway acceleration during magnetic reconnection in tokamaks

    International Nuclear Information System (INIS)

    Helander, P; Eriksson, L-G; Andersson, F

    2002-01-01

    In this paper, the basic theory of runaway electron production is reviewed and recent progress is discussed. The mechanisms of primary and secondary generation of runaway electrons are described and their dynamics during a tokamak disruption is analysed, both in a simple analytical model and through numerical Monte Carlo simulation. A simple criterion for when these mechanisms generate a significant runaway current is derived, and the first self-consistent simulations of the electron kinetics in a tokamak disruption are presented. Radial cross-field diffusion is shown to inhibit runaway avalanches, as indicated in recent experiments on JET and JT-60U. Finally, the physics of relativistic post-disruption runaway electrons is discussed, in particular their slowing down due to emission of synchrotron radiation, and their ability to produce electron-positron pairs in collisions with bulk plasma ions and electrons

  14. Decolourization of Rhodamine B: A swirling jet-induced cavitation combined with NaOCl.

    Science.gov (United States)

    Mancuso, Giuseppe; Langone, Michela; Laezza, Marco; Andreottola, Gianni

    2016-09-01

    A hydrodynamic cavitation reactor (Ecowirl) based on swirling jet-induced cavitation has been used in order to allow the degradation of a waste dye aqueous solution (Rhodamine B, RhB). Cavitation generated by Ecowirl reactor was directly compared with cavitation generated by using multiple hole orifice plates. The effects of operating conditions and parameters such as pressure, pH of dye solution, initial concentration of RhB and geometry of the cavitating devices on the degradation rate of RhB were discussed. In similar operative conditions, higher extents of degradation (ED) were obtained using Ecowirl reactor rather than orifice plate. An increase in the ED from 8.6% to 14.7% was observed moving from hole orifice plates to Ecowirl reactor. Intensification in ED of RhB by using hydrodynamic cavitation in presence of NaOCl as additive has been studied. It was found that the decolourization was most efficient for the combination of hydrodynamic cavitation and chemical oxidation as compared to chemical oxidation and hydrodynamic cavitation alone. The value of ED of 83.4% was reached in 37min using Ecowirl combined with NaOCl (4.0mgL(-1)) as compared to the 100min needed by only mixing NaOCl at the same concentration. At last, the energetic consumptions of the cavitation devices have been evaluated. Increasing the ED and reducing the treatment time, Ecowirl reactor resulted to be more energy efficient as compared to hole orifice plates, Venturi and other swirling jet-induced cavitation devices, as reported in literature. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. JET Project: progress in construction and management

    International Nuclear Information System (INIS)

    Bertolini, E.

    1978-01-01

    The JET Project of the European Community aims to construct and operate one of the largest Tokamak Devices foreseen at present in the field of Fusion Research. The aim of the experiment is to produce and study plasma conditions approaching those needed in a thermonuclear reactor and therefore will involve operation with deuterium--tritium gas

  16. A new Disruption Mitigation System for deuterium–tritium operation at JET

    Energy Technology Data Exchange (ETDEWEB)

    Kruezi, Uron, E-mail: uron.kruezi@ccfe.ac.uk [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Jachmich, Stefan [Laboratory for Plasma Physic, ERM/KMS, B-1000 Brussels (Belgium); Koslowski, Hans Rudolf [Forschungszentrum Jülich GmbH, IEK-4, 52425 Jülich (Germany); Lehnen, Michael [ITER Organization, Route de Vinon-sur-Verdon, CS90046, 13067 St. Paul Lez Durance Cedex (France); Brezinsek, Sebastijan [Forschungszentrum Jülich GmbH, IEK-4, 52425 Jülich (Germany); Matthews, Guy [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom)

    2015-10-15

    Highlights: • A Disruption Mitigation System based on massive gas injections has been designed. • The DMS has been installed at the JET-tokamak for routine machine protection. • The DMS is capable of a throughput of up to 4.6 kPa m{sup 3}. • The new DMS is compatible with the deuterium–tritium operation at JET. - Abstract: Disruptions, the fast accidental losses of plasma current and stored energy in tokamaks, represent a significant risk to the mechanical structure as well as the plasma facing components of reactor-scale fusion facilities like ITER. At JET, the tokamak experiment closest to ITER in terms of operating parameters and size, massive gas injection has been established as a disruption mitigation method. As a “last resort” measure it reduces thermal and electromagnetic loads during disruptions which can potentially have a serious impact on the beryllium and tungsten plasma-facing materials of the main chamber and divertor. For the planned deuterium–tritium experiments, a new Disruption Mitigation System (DMS) has been designed and installed and is presented in this article. The new DMS at JET consists of an all metal gate valve compatible with gas injections, a fast high pressure eddy current driven valve, a high voltage power supply and a gas handling system providing six supply lines for pure and mixed noble and flammable gases (Ar, Ne, Kr, D{sub 2}, etc.). The valve throughput varies with the injection pressure and gas type (efficiency – injected/charged gas 50–97%); the maximum injected amount of gas is approximately 4.6 kPa m{sup 3} (at maximum system pressure of 5.0 MPa).

  17. A new Disruption Mitigation System for deuterium–tritium operation at JET

    International Nuclear Information System (INIS)

    Kruezi, Uron; Jachmich, Stefan; Koslowski, Hans Rudolf; Lehnen, Michael; Brezinsek, Sebastijan; Matthews, Guy

    2015-01-01

    Highlights: • A Disruption Mitigation System based on massive gas injections has been designed. • The DMS has been installed at the JET-tokamak for routine machine protection. • The DMS is capable of a throughput of up to 4.6 kPa m"3. • The new DMS is compatible with the deuterium–tritium operation at JET. - Abstract: Disruptions, the fast accidental losses of plasma current and stored energy in tokamaks, represent a significant risk to the mechanical structure as well as the plasma facing components of reactor-scale fusion facilities like ITER. At JET, the tokamak experiment closest to ITER in terms of operating parameters and size, massive gas injection has been established as a disruption mitigation method. As a “last resort” measure it reduces thermal and electromagnetic loads during disruptions which can potentially have a serious impact on the beryllium and tungsten plasma-facing materials of the main chamber and divertor. For the planned deuterium–tritium experiments, a new Disruption Mitigation System (DMS) has been designed and installed and is presented in this article. The new DMS at JET consists of an all metal gate valve compatible with gas injections, a fast high pressure eddy current driven valve, a high voltage power supply and a gas handling system providing six supply lines for pure and mixed noble and flammable gases (Ar, Ne, Kr, D_2, etc.). The valve throughput varies with the injection pressure and gas type (efficiency – injected/charged gas 50–97%); the maximum injected amount of gas is approximately 4.6 kPa m"3 (at maximum system pressure of 5.0 MPa).

  18. Direct measurements of damping rates and stability limits for low frequency MHD modes and Alfven Eigenmodes in the JET tokamak

    International Nuclear Information System (INIS)

    Fasoli, A.F.; Testa, D.; Jaun, A.; Sharapov, S.; Gormezano, C.

    2001-01-01

    The linear stability properties of global modes that can be driven by resonant energetic particles or by the bulk plasma are studied using an external excitation method based on the JET saddle coil antennas. Low toroidal mode number, stable plasma modes are driven by the saddle coils and detected by magnetic probes to measure their structure, frequency and damping rate, both in the Alfven Eigenmode (AE) frequency range and in the low frequency Magneto-Hydro-Dynamic (MHD) range. For AEs, the dominant damping mechanisms are identified for different plasma conditions of relevance for reactors. Spectra and damping rates of low frequency MHD modes that are localized at the foot of the internal transport barrier and can affect the plasma performance in advanced tokamak scenarios have been directly measured for the first time. This gives the possibility of monitoring in real time the approach to the instability boundary. (author)

  19. Edge plasma physical investigations of tokamak plasmas in CRIP

    International Nuclear Information System (INIS)

    Bakos, J.; Ignacz, P.; Koltai, L.; Paszti, F.; Petravich, G.; Szigeti, J.; Zoletnik, S.

    1988-01-01

    The results of the measurements performed in the field of thermonuclear high temperature plasma physics in CRIP (Hungary) are summarized. In the field of the edge plasma physics solid probes were used to test the external zone of plasma edges, and atom beams and balls were used to investigate both the external and internal zones. The plasma density distribution was measured by laser blow-off technics, using Na atoms, which are evaporated by laser pulses. The excitation of Na atom ball by tokamak plasma gives information on the status of the plasma edge. The toroidal asymmetry of particle transport in tokamak plasma was measured by erosion probes. The evaporated and transported impurities were collected on an other part of the plasma edge and were analyzed by SIMS and Rutherford backscattering. The interactions in plasma near the limiter were investigated by a special limiter with implemented probes. Recycling and charge exchange processes were measured. Disruption phenomena of tokamak plasma were analyzed and a special kind of disruptions, 'soft disruptions' and the related preliminary perturbations were discovered. (D.Gy.) 10 figs

  20. Advanced statistics for tokamak transport colinearity and tokamak to tokamak variation

    International Nuclear Information System (INIS)

    Riedel, K.S.

    1989-03-01

    This is a compendium of three separate articles on the statistical analysis of tokamak transport. The first article is an expository introduction to advanced statistics and scaling laws. The second analyzes two important problems of tokamak data---colinearity and tokamak to tokamak variation in detail. The third article generalizes the Swamy random coefficient model to the case of degenerate matrices. Three papers have been processed separately

  1. Study of runaway electron generation during major disruptions in JET

    Czech Academy of Sciences Publication Activity Database

    Plyusnin, V.V.; Riccardo, V.; Jaspers, R.; Alper, B.; Kiptily, V.G.; Mlynář, Jan; Popovichev, S.; de La Luna, E.; Andersson, F.

    2006-01-01

    Roč. 46, č. 2 (2006), s. 277-284 ISSN 0029-5515 Institutional research plan: CEZ:AV0Z2043910 Keywords : JET * tokamak * fusion * dicsruption * runaway electrons * tomography Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.839, year: 2006

  2. Plasma internal inductance dynamics in a tokamak

    International Nuclear Information System (INIS)

    Romero, J.A.

    2010-01-01

    A lumped parameter model for tokamak plasma current and inductance time evolution as a function of plasma resistance, non-inductive current drive sources and boundary voltage or poloidal field coil current drive is presented. The model includes a novel formulation leading to exact equations for internal inductance and plasma current dynamics. Having in mind its application in a tokamak inductive control system, the model is expressed in state space form, the preferred choice for the design of control systems using modern control systems theory. The choice of system states allows many interesting physical quantities such as plasma current, inductance, magnetic energy, and resistive and inductive fluxes be made available as output equations. The model is derived from energy conservation theorem, and flux balance theorems, together with a first order approximation for flux diffusion dynamics. The validity of this approximation has been checked using experimental data from JET showing an excellent agreement.

  3. Jet Inlet Efficiency

    Science.gov (United States)

    2013-08-08

    AFRL-RW-EG-TR-2014-044 Jet Inlet Efficiency Nigel Plumb Taylor Sykes-Green Keith Williams John Wohleber Munitions Aerodynamics Sciences...CONTRACT NUMBER N/A 5b. GRANT NUMBER N/A 5c. PROGRAM ELEMENT NUMBER N/A 6. AUTHOR(S) Nigel Plumb Taylor Sykes-Green Keith Williams John

  4. JET:Preparing the future in fusion

    Czech Academy of Sciences Publication Activity Database

    Mlynář, Jan; Ongena, J.; Ďuran, Ivan; Hron, Martin; Pánek, Radomír; Petržílka, Václav; Žáček, František

    2004-01-01

    Roč. 54, suppl.C (2004), C28-C38 ISSN 0011-4626. [Symposium on Plasma Physics and Technology /21st/. Praha, 14.06.2004-17.06.2004] R&D Projects: GA ČR GA202/04/0360 Institutional research plan: CEZ:AV0Z2043910 Keywords : fusion, tokamak, JET EFDA, ITER Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.292, year: 2004

  5. Technical design of a solid tungsten divertor row for the ITER-like wall in the JET tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Mertens, P.; Knaup, M.; Neubauer, O.; Sadakov, S.; Schweer, B.; Terra, A.; Samm, U. [Forschungszentrum Juelich, Association EURATOM-FZJ (DE). Inst. fuer Energieforschung IEF-4 (Plasmaphysik); Pintsuk, G. [Forschungszentrum Juelich, Association EURATOM-FZJ (DE). Inst. fuer Energieforschung IEF-2 (Werkstoffstruktur und Eigenschaften)

    2009-07-01

    ITER (originally International Thermonuclear Experimental Reactor) is now under construction in Cadarache, France. In order to investigate plasma scenarios compatible with an ITER relevant mix of materials, a new, complete inner wall will be installed in the JET tokamak vessel (Culham, UK) in 2010. The plasmafacing components in the main chamber will be made of beryllium whereas the exposed areas in the divertor shall be made of tungsten, mostly of tungsten coatings on a carbon-fibre composite substrate. A notable exception is the central row of tiles where the outer strike point is located. Fig. 1 illustrates it with a camera view during a suitable discharge which shows the emission of atomic hydrogen, hence the main interaction regions. Plasma-facing components at this position are exposed to very high particle fluxes which cause material sputtering, and to extremely high heat loads without active cooling, which is not available. It was accordingly decided to resort to solid tungsten in this particular case. An overview of the conceptual design was presented earlier. Manufacturing is just starting, so the technical design has been frozen to the largest extent as presented in the following. (orig.)

  6. Ion temperature profiles in JET

    International Nuclear Information System (INIS)

    Hellermann, M. von; Mandl, W.; Summers, H.P.; Weisen, H.

    1989-01-01

    The results presented in this paper have shown some extreme cases of ion temperature profiles illustrating the different operation modes of the JET tokamak. In the three examples of low-density high temperature, high-density moderates and high-density high-confinement plasmas comparable values of a maximum fusion product n d T i τ E in the order of 10 20 keV m -3 sec are achieved. (author) 1 ref., 7 figs

  7. Evaluation of Cetane Improver Additive in Alternative Jet Fuel Blends

    Science.gov (United States)

    2016-07-01

    3 EVALUATION AND DATA ANALYSIS ...DISTRIBUTION A. Approved for public release: distribution unlimited. Evaluation and Data Analysis Derived Cetane Number (DCN) DCN was tested IAW ASTM D6890...100 ppm CI #2 0.00 1 n/a SIP/Jet A + 500 ppm CI #2 0.00 >4 n/a Jet A 0.66 ə n/a Jet A + 100 ppm CI #1 100.23 ə 105 Jet A + 500 ppm CI #1 100.09 > 4P

  8. Fast ions and momentum transport in JET tokamak plasmas

    International Nuclear Information System (INIS)

    Salmi, A.

    2012-01-01

    Fast ions are an inseparable part of fusion plasmas. They can be generated using electromagnetic waves or injected into plasmas as neutrals to heat the bulk plasma and to drive toroidal rotation and current. In future power plants fusion born fast ions deliver the main heating into the plasma. Understanding and controlling the fast ions is of crucial importance for the operation of a power plant. Furthermore, fast ions provide ways to probe the properties of the thermal plasma and get insight of its confinement properties. In this thesis, numerical code packages are used and developed to simulate JET experiments for a range of physics issues related to fast ions. Namely, the clamping fast ion distribution at high energies with RF heating, fast ion ripple torque generation and the toroidal momentum transport properties using NBI modulation technique are investigated. Through a comparison of numerical simulations and the JET experimental data it is shown that the finite Larmor radius effects in ion cyclotron resonance heating are important and that they can prevent fast ion tail formation beyond certain energy. The identified mechanism could be used for tailoring the fast ion distribution in future experiments. Secondly, ASCOT simulations of NBI ions in a ripple field showed that most of the reduction of the toroidal rotation that has been observed in the JET enhanced ripple experiments could be attributed to fast ion ripple torque. Finally, fast ion torque calculations together with momentum transport analysis have led to the conclusion that momentum transport in not purely diffusive but that a convective component, which increases monotonically in radius, exists in a wide range of JET plasmas. Using parameter scans, the convective transport has been shown to be insensitive to collisionality and q-profile but to increase strongly against density gradient. (orig.)

  9. Fast ions and momentum transport in JET tokamak plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Salmi, A.

    2012-07-01

    Fast ions are an inseparable part of fusion plasmas. They can be generated using electromagnetic waves or injected into plasmas as neutrals to heat the bulk plasma and to drive toroidal rotation and current. In future power plants fusion born fast ions deliver the main heating into the plasma. Understanding and controlling the fast ions is of crucial importance for the operation of a power plant. Furthermore, fast ions provide ways to probe the properties of the thermal plasma and get insight of its confinement properties. In this thesis, numerical code packages are used and developed to simulate JET experiments for a range of physics issues related to fast ions. Namely, the clamping fast ion distribution at high energies with RF heating, fast ion ripple torque generation and the toroidal momentum transport properties using NBI modulation technique are investigated. Through a comparison of numerical simulations and the JET experimental data it is shown that the finite Larmor radius effects in ion cyclotron resonance heating are important and that they can prevent fast ion tail formation beyond certain energy. The identified mechanism could be used for tailoring the fast ion distribution in future experiments. Secondly, ASCOT simulations of NBI ions in a ripple field showed that most of the reduction of the toroidal rotation that has been observed in the JET enhanced ripple experiments could be attributed to fast ion ripple torque. Finally, fast ion torque calculations together with momentum transport analysis have led to the conclusion that momentum transport in not purely diffusive but that a convective component, which increases monotonically in radius, exists in a wide range of JET plasmas. Using parameter scans, the convective transport has been shown to be insensitive to collisionality and q-profile but to increase strongly against density gradient. (orig.)

  10. Tokamaks - Third Edition

    International Nuclear Information System (INIS)

    Rogister, A L

    2004-01-01

    an introduction to diagnostics for tokamaks. The complexity of fusion plasmas is attested to by the discovery of new phenomena and new operational regimes as machine size and power increased and the diagnostic tools improved over the forty years of research on magnetic confinement. The history of those discoveries in the devices which have been built worldwide after the results obtained on the first tokamaks at the Kurchatov Institute had been confirmed is outlined in chapters 11-12. Particular emphasis is naturally given to the results from the larger tokamaks: ASDEX Upgrade, DIII-D, TFTR, JT-60/JT-60U and JET. Chapter 13 is devoted to the International Tokamak Experimental Reactor and prospects beyond ITER. Examples of operational regimes and of often unexpected phenomena are the linear and saturated ohmic confinement modes, confinement degradation when auxiliary heating is applied, the high energy confinement mode, the formation of internal transport barriers in weak or negative central shear discharges, sawtooth relaxations, disruptions, multifaceted asymmetric radiation from the edge, edge localised modes, etc. The relevant observations are described very thoroughly with the support of numerous selected figures and their physical interpretation, a major topic of the book, is carefully discussed on the basis of simplified but convincing mathematical models. With respect to the previous edition (1997), a few additions have been introduced; those concern plasma rotation (section 3.13), internal transport barriers (4.14), the role of radial electric field shear (4.19), turbulence simulations (4.21), impurity transport (4.22) and neoclassical drive of tearing modes (7.3). It is my personal feeling that some of those additions should have been somewhat more elaborated. A few pages have finally been added concerning the TCV, START, MAST, NSTX and ASDEX Upgrade tokamaks. With this book, John Wesson offers the fusion community a very precious and thorough survey of

  11. Ubiquity of non-diffusive momentum transport in JET H-modes

    NARCIS (Netherlands)

    Weisen, H.; Camenen, Y.; Salmi, A.; Versloot, T. W.; de Vries, P. C.; Maslov, M.; Tala, T.; Beurskens, M.; Giroud, C.; JET-EFDA Contributors,

    2012-01-01

    A broad survey of the experimental database of neutral beam heated baseline H-modes and hybrid scenarios in the JET tokamak has established the ubiquity of non-diffusive momentum transport mechanisms in rotating plasmas. As a result of their presence, the normalized angular frequency gradient R

  12. Local magnetic shear control in a tokamak via fast wave minority ion current drive: Theory and experiments in JET

    International Nuclear Information System (INIS)

    Bhatnagar, V.P.; Start, D.F.H.; Jacquinot, J.; Chaland, F.; Cherubini, A.; Porcelli, F.

    1994-01-01

    When an ion cyclotron resonance heating (ICRH) antenna array is phased (Δ Φ ≠ 0 or π), the excited asymmetric k parallel spectrum can drive non-inductive currents by interaction of fast waves both with electrons (transit time magnetic pumping (e-TTMP) and Landau damping (e-LD)) and with ions at minority (fundamental) or harmonic cyclotron resonances, depending upon the scenario. On the basis of earlier theories, a simplified description is presented that includes the minority ion and electron current drive effects simultaneously in a 3-D ray tracing calculation in the tokamak geometry. The experimental results of sawtooth stabilization or destabilization in JET using the minority ion current drive scheme are presented. This scheme allows a modification of the local current density gradient (or the magnetic shear) at the q = 1 surface resulting in a control of a sawteeth. The predictions of the above model of current drive and its effects on sawtooth period calculated in conjunction with a model of stability of internal resistive kink modes, that encompasses the effects of both the fast particle pressure and the local (q = 1) magnetic shear, are found to be qualitatively in good agreement with the experimental results. Further, the results are discussed of our model of fast wave current drive scenarios of magnetic shear reversal with a view to achieving long duration high confinement regimes in the forthcoming experimental campaign on JET. Finally, the results are presented of minority current drive for sawtooth control in next step devices such as the International Thermonuclear Experimental Reactor (ITER). (author). 44 refs, 23 figs, 3 tabs

  13. Modelling magnetic forces during asymmetric vertical displacement events at JET

    International Nuclear Information System (INIS)

    Riccardo, V.; Walker, S.; Noll, P.

    2000-01-01

    Asymmetric vertical disruption events (AVDEs) are fortunately rare, but can induce large lateral forces which can cause significant mechanical damage to tokamaks. In this paper we present a simple model which allows the lateral forces generated during such a disruption to be estimated as a function of relatively easily obtained electromagnetic parameters: the asymmetries in the vertical current moment. This model is validated by using it to predict the displacement history of the JET tokamak caused by a number of major AVDEs. It is shown that the predicted forces and displacements agree well with quantities measured during these disruptions. One conclusion from the model is that the maximum sideways displacement scales with the product of the plasma current and the toroidal field, and this recipe is now used at JET to assess a priori the hazards of performing high current and high field pulses when they are known to be likely to disrupt. (author)

  14. Recent results and near-term expectations in Tokamak fusion research in the U.S., Europe, and Japan

    International Nuclear Information System (INIS)

    Meade, D.

    1993-01-01

    The development of fusion is often thought about in terms of three different activities: scientific feasibility, engineering feasibility, and economic feasibility. This paper discusses the scientific feasibility of fusion. Reactor temperatures, reactor densities and confinement, particle control, plasma power handling, and self-heating are some of the issues examined. Collaboration and results from research at the Tokamak Fusion Test Reactor (TFTR) at Princeton, the JT-60U in Japan, and JET, the Joint European Torus Tokamak in Oxford are presented

  15. Tokamak

    International Nuclear Information System (INIS)

    Wesson, John.

    1996-01-01

    This book is the first compiled collection about tokamak. At first chapter tokamak is represented from fusion point of view and also the necessary conditions for producing power. The following chapters are represent plasma physics, the specifications of tokamak, plasma heating procedures and problems related to it, equilibrium, confinement, magnetohydrodynamic stability, instabilities, plasma material interaction, plasma measurement and experiments regarding to tokamak; an addendum is also given at the end of the book

  16. Relative merits of size, field, and current on ignited tokamak performance

    International Nuclear Information System (INIS)

    Uckan, N.A.

    1988-01-01

    A simple global analysis is developed to examine the relative merits of size (L = a or R/sub 0 /), field (B/sub 0 /), and current (I) on ignition regimes of tokamaks under various confinement scaling laws. Scalings of key parameters with L, B/sub 0 /, and I are presented at several operating points, including (a) optimal path to ignition (saddle point), (b) ignition at minimum beta, (c) ignition at 10 keV, and (d) maximum performance at the limits of density and beta. Expressions for the saddle point and the minimum conditions needed for ohmic ignition are derived analytically for any confinement model of the form tau/sub E/ ∼ n/sup x/T/sup y/. For a wide range of confinement models, the ''figure of merit'' parameters and I are found to give a good indication of the relative performance of the devices where q* is the cylindrical safety factor. As an illustration, the results are applied to representative ''CIT'' (as a class of compact, high-field ignition tokamaks) and ''Super-JETs'' [a class of large-size (few x JET), low-field, high-current (≥20-MA) devices.

  17. Control, data acquisition and analysis for the JET neutral injection test bed

    International Nuclear Information System (INIS)

    Jones, T.T.C.; Brenan, P.R.; Rodgers, M.E.; Stork, D.; Young, I.D.

    1985-01-01

    The Neutral Injection Test-Bed (NITB) is a major experimental assembly in support of the Neutral Beam Heating Programme for JET. In addition to its prime function of testing the Neutral Injection hardware, the Test Bed serves as the prototype to test the computer control and data acquisition system, which is described in this paper. The software system has been written in a portable, data-driven manner with the aim to adapt it, with only minor modifications to the operation of the first. Neutral Injection Beamline on JET, which will involve operation both synchronous and asynchronous with that of the JET Tokamak

  18. Neoclassical alpha-particle losses in tokamaks allowing for large orbit widths

    International Nuclear Information System (INIS)

    Cox, M.; O'Brien, M.R.; Zaitsev, F.S.

    1994-01-01

    Alpha-particle physics is of particular importance now that research into controlled fusion has reached thermonuclear parameters and D-T fuel has been used in JET and TFTR. Here we address the important topic of α-particle transport: if transport is too low helium ash accumulates quenching the burn; if it is too high heating of the plasma by fast α-particles is insufficient to maintain the burn. We give results from simulations of α-particle distributions (f α ) which self-consistently treat α-particle birth, collisional slowing down and neoclassical radial transport. The (steady-state) f α is calculated by the FPP code as a function of speed (v), pitch-angle (θ) and flux surface radius (r). This code is based on a 3D Fokker-Planck theory of 'banana regime' neoclassical effects in tokamaks which can treat large deviations of fast ion orbits from flux surfaces and non-Maxwellian distributions. The code reproduces standard neoclassical results for Maxwellian distributions in the large aspect ratio (ε) and small orbit width (Δ) limits (e.g. radial fluxes, conductivities and bootstrap currents), but can also be used for small ε and large Δ which are difficult to treat analytically. The code is particularly useful for α-particle studies as (a) the experimental evidence is that fast ion transport is usually consistent with neoclassical theory, unlike electron or thermal ion transport, and (b) trapped fast ion orbits can deviate greatly from flux surfaces. An alternative to this Fokker-Planck treatment is Monte Carlo modelling. However, representation of the detailed structure of f α (θ,v,r) would require very large number of particles, and hence be very slow. Calculations have been made for parameters typical of TFTR, JET, SSTR (an 'advanced tokamak' reactor) and STR (a tight aspect ratio or 'spherical' tokamak reactor, though only the JET results are discussed in detail. (author) 4 refs., 4 figs

  19. Numerical Simulation of Neoclassical Currents, Parallel Viscosity, and Radial Current Balance in Tokamak Plasmas

    International Nuclear Information System (INIS)

    Kiviniemi, T.

    2001-01-01

    One of the principal problems en route to a fusion reactor is that of insufficient plasma confinement, which has lead to both theoretical and experimental research into transport processes in the parameter range relevant for fusion energy production. The neoclassical theory of tokamak transport is well-established unlike the theory of turbulence driven anomalous transport in which extensive progress has been made during last few years. So far, anomalous transport has been dominant in experiments, but transport may be reduced to the neoclassical level in advanced tokamak scenarios. This thesis reports a numerical study of neoclassical fluxes, parallel viscosity, and neoclassical radial current balance in tokamaks. Neoclassical parallel viscosity and particle fluxes are simulated over a wide range of collisionalities, using the fully kinetic five-dimensional neoclassical orbit-following Monte Carlo code ASCOT. The qualitative behavior of parallel viscosity derived in earlier analytic models is shown to be incorrect for high poloidal Mach numbers. This is because the poloidal dependence of density was neglected. However, in high Mach number regime, it is the convection and compression terms, rather than the parallel viscosity term, that are shown to dominate the momentum balance. For fluxes, a reasonable agreement between numerical and analytical results is found in the collisional parameter regime. Neoclassical particle fluxes are additionally studied in the banana regime using the three-dimensional Fokker-Planck code DEPORA, which solves the drift-kinetic equation with finite differencing. Limitations of the small inverse aspect ratio approximation adopted in the analytic theory are addressed. Assuming that the anomalous transport is ambipolar, the radial electric field and its shear at the tokamak plasma edge can be solved from the neoclassical radial current balance. This is performed both for JET and ASDEX Upgrade tokamaks using the ASCOT code. It is shown that

  20. Systems for the safe operation of the JET tokamak with tritium

    International Nuclear Information System (INIS)

    Stork, D.; Ageladarakis, P.; Bell, A.C.

    1999-01-01

    In 1997, the JET device was operated for an extensive campaign with deuterium-tritium (D-T) plasmas (the DTE1 campaign). A comprehensive network of machine protection systems was necessary so that this experimental campaign could be executed safely without damage to the machine or release of activated material. This network had been developed over many years of JET deuterium plasma operation and therefore the modifications for D-T operation was not a significant problem. The DTE1 campaign was executed successfully and safely and the machine protection systems proved reliable and robust and, in the limited cases where they were required to act, functioned correctly. The machine protection systems at JET are described and their categorisation and development over time are summarised. The management, commissioning and operational experience during DTE1 are discussed and some examples of fault scenarios are described. The experience with protection systems at JET highlights the importance of correct design and philosophy decisions being taken at an early stage. It is shown that this experience will be invaluable data input to the safe operation of future large fusion machines. (orig.)

  1. Steady-state operation requirements of tokamak fusion reactor concepts

    International Nuclear Information System (INIS)

    Knobloch, A.F.

    1991-06-01

    In the last two decades tokamak conceptual reactor design studies have been deriving benefit from progressing plasma physics experiments, more depth in theory and increasing detail in technology and engineering. Recent full-scale reactor extrapolations such as the US ARIES-I and the EC Reference Reactor study provide information on rather advanced concepts that are called for when economic boundary conditions are imposed. The ITER international reactor design activity concentrated on defining the next step after the JET generation of experiments. For steady-state operation as required for any future commercial tokamak fusion power plants it is essential to have non-inductive current drive. The current drive power and other internal power requirements specific to magnetic confinement fusion have to be kept as low as possible in order to attain a competitive overall power conversion efficiency. A high plasma Q is primarily dependent on a high current drive efficiency. Since such conditions have not yet been attained in practice, the present situation and the degree of further development required are characterized. Such development and an appropriately designed next-step tokamak reactor make the gradual realization of high-Q operation appear feasible. (orig.)

  2. Overview of JET results

    International Nuclear Information System (INIS)

    Pamela, J.

    2003-01-01

    Scientific and technical activities on JET focus on the issues likely to affect the ITER design and operation. The physics of the ITER reference mode of operation, the ELMy H-mode, has progressed significantly: the extrapolation of ELM size to ITER has been re-evaluated; NTMs have been shown to be metastable in JET, and can be avoided via sawtooth destabilisation by ICRH; α-simulation experiments were carried out by accelerating 4 He beam ions by ICRH, providing a new tool for fast particle and MHD studies with up to 80-90% of plasma heating by fast 4 He ions. With or without impurity seeding, quasi-steady sate high confinement (H 98 =1), high density (n e /n GR = 0.9-1) and high β (β N =2) ELMy H-mode has been achieved by operating near the ITER triangularity (δ∼0.40-0.5) and safety factor (q 95 ∼3), at Z eff ∼1.5-2. In Advanced Tokamak scenarios, internal transport barriers are now characterised in real time with a new criterion ρ* T ; tailoring of the current profile with LHCD provides reliable access to a variety of q profiles, with significantly lowered access power for barrier formation; rational q surfaces appear to be associated with ITB formation; Alfven cascades are observed in RS plasmas, providing an identification of q profile evolution; plasmas with 'current holes' were observed and explained by modelling. Transient high confinement Advanced Tokamak regimes with H89=3.3, β N =2.4 and ITER relevant q<5 are achievable in reversed magnetic shear. Quasistationary internal transport barriers are developed with full non-inductive current drive, including ∼50% bootstrap current. Record duration of ITBs was achieved, up to 11 s, approaching the resistive time. Pressure and current profiles of Advanced Tokamak regimes are controlled by a real time feedback system, in separate experiments. The erosion and co-deposition data base progressed significantly, in particular with a new quartz microbalance diagnostic allowing shot by shot measurements of

  3. Evidence of Inward Toroidal Momentum Convection in the JET Tokamak

    DEFF Research Database (Denmark)

    Tala, T.; Zastrow, K.-D.; Ferreira, J.

    2009-01-01

    Experiments have been carried out on the Joint European Torus tokamak to determine the diffusive and convective momentum transport. Torque, injected by neutral beams, was modulated to create a periodic perturbation in the toroidal rotation velocity. Novel transport analysis shows the magnitude...... and profile shape of the momentum diffusivity are similar to those of the ion heat diffusivity. A significant inward momentum pinch, up to 20 m/s, has been found. Both results are consistent with gyrokinetic simulations. This evidence is complemented in plasmas with internal transport barriers....

  4. Toroidal rotation braking with n = 1 magnetic perturbation field on JET

    DEFF Research Database (Denmark)

    Sun, Y; Liang, Y; Koslowski, H R

    2010-01-01

    A strong toroidal rotation braking has been observed in plasmas with application of an n = 1 magnetic perturbation field on the JET tokamak. Calculation results from the momentum transport analysis show that the torque induced by the n = 1 perturbation field has a global profile. The maximal value...

  5. Pneumatic pellet injectors for TFTR and JET

    International Nuclear Information System (INIS)

    Combs, S.K.; Milora, S.L.

    1986-01-01

    This paper describes the development of pneumatic hydrogen pellet injectors for plasma fueling applications on the Tokamak Fusion Test Reactor (TFTR) and the Joint European Torus (JET). The performance parameters of these injectors represent an extension of previous experience and include pellet sizes in the range 2-6 mm in diameter and speeds approaching 2 km/s. Design features and operating characteristics of these pneumatic injectors are presented

  6. JET Tokamak, preparation of a safety case for tritium operations

    Energy Technology Data Exchange (ETDEWEB)

    Boyer, Helen, E-mail: helen.boyer@ccfe.ac.uk [CCFE, Culham Science Centre (United Kingdom); Plummer, David; Johnston, Jane [CCFE, Culham Science Centre (United Kingdom)

    2016-11-01

    Highlights: • A safety case incorporating technical and ITER related upgrades. • Hazard analysis reworked to include new modelling assessments. • Fitness for purpose assessment of safety controls. - Abstract: A new Safety Case is required to permit tritium operations on JET during the forthcoming DTE2 campaign. The outputs, benefits and lessons learned associated with the production of this Safety Case are presented. The changes that have occurred to the Safety Case methodology since the last JET tritium Safety Case are reviewed. Consideration is given to the effects of modifications, particularly ITER related changes, made to the JET and the impact these have on the hazard assessments as well as normal operations. Several specialized assessments, including recent MELCOR modelling, have been undertaken to support the production of this Safety Case and the impact of these assessments is outlined. Discussion of the preliminary actions being taken to progress implementation of this Safety Case is provided, highlighting new methods to improve the dissemination of the key Safety Case results to the plant operators. Finally, the work required to complete this Safety Case, before the next tritium campaign, is summarized.

  7. JET joint undertaking. Annual report 1986

    International Nuclear Information System (INIS)

    1987-06-01

    The scientific, technical, and administrative status of the JET tokamak program is summarized. The Euratom and international fusion programs are outlined. Main performance results are: volume average electron density = 0.5 (10 20 m -3 ); central electron temperature = 8.0 keV; central ion temperature = 12.5 keV; global energy confinement time = 0.9 sec; and fusion parameter performance parameter (simultaneous temperature, density, and energy confinement time) = 2.0 (10 20 m -3 keV

  8. Alpha particle losses during sawtooth activity in Tokamaks

    International Nuclear Information System (INIS)

    Anderson, D.; Lisak, M.

    1988-01-01

    The time evolution of the direct losses of fusion produced alpha particles in Tokamak plasmas characterized by sawtooth activity is investigated. The alpha particle loss rate during a sawtooth period is predicted to change invertedly with the change in bulk plasma parameters but also to contain a characteristic burst at the sawtooth crash. The spectrum of the lost alpha particles is also discussed. The predictions for the time evolution and the spectrum of the losses are in qualitative agreement with recently obtained losses of 15 MeV fusion produced protons in JET. (authors)

  9. On the physics of runaway particles in JET and MAST

    International Nuclear Information System (INIS)

    Helander, P.; Akers, R.J.; Gimblett, C.G.; Tournianski, M.R.; Byrom, C.; Eriksson, L.-G.; Andersson, F.

    2003-01-01

    This paper explores the physics of runaway particles observed in MAST and JET. During internal reconnection events in MAST, it is observed that the ion distribution function, as measured by a neutral-particle analyser, develops a high-energy tail, which subsequently decays on the time scale of collisional slowing down. These observations are explained in terms of runaway ion acceleration in the electric field induced by the reconnection - a phenomenon predicted theoretically by Furth and Rutherford in 1972 but not commonly noted in tokamaks. In JET, long-lived post-disruption currents carried by runaway electrons have been observed to decay on a time scale of 1-2 s. A relativistic kinetic theory is developed to explain this decay as a consequence of the combined action of Coulomb collisions and synchrotron radiation emission. It is also pointed out that substantial electron-positron pair production should occur in such discharges, which have also been made more recently on JT-60U. In fact, tokamaks may be the largest positron repositories made by man. (author)

  10. Jet Joint Undertaking. Annual report 1990

    International Nuclear Information System (INIS)

    1991-05-01

    The Joint European Torus is the largest project in the coordinated fusion programme of the European Atomic Energy Community (EURATOM). A brief general introduction provides an overview of the planning of the Report. This is followed by a description of JET and the Euratom and International Fusion Programmes, which summarize the main features of the JET apparatus and its experimental programme and explains the position of the Project in the overall Euratom programme. In addition, this relates and compares JET to other large fusion devices throughout the world. The following section reports on the technical status of the machine including: technical changes and achievements during 1989; details of the operational organization of experiments and pulse statistics; and progress on enhancements in machine systems for future operation. This is followed by the results of JET operations in 1990 under various operating conditions, including ohmic heating, radio-frequency (RF) heating, neutral beam (NB) heating and various combined scenarios in different magnetic field configurations; the overall global and local behaviour observed; and the progress towards reactor conditions. In particular, the comparative performance between JET and other tokamaks, in terms of the triple fusion product, shows the substantial achievements made by JET since the start of operations in 1983. The second part of the Report explains the organization and management of the Project and describes the administration of JET. In particular, it sets out the budget situation; contractual arrangements during 1990; and details of the staffing arrangements and complement

  11. Ideal magnetohydrodynamic simulations of unmagnetized dense plasma jet injection into a hot strongly magnetized plasma

    OpenAIRE

    Liu, Wei; Hsu, Scott C.

    2010-01-01

    We present results from three-dimensional ideal magnetohydrodynamic simulations of unmagnetized dense plasma jet injection into a uniform hot strongly magnetized plasma, with the aim of providing insight into core fueling of a tokamak with parameters relevant for ITER and NSTX (National Spherical Torus Experiment). Unmagnetized dense plasma jet injection is similar to compact toroid injection but with much higher plasma density and total mass, and consequently lower required injection velocit...

  12. Mechanism for rapid sawtooth crashes in tokamaks

    International Nuclear Information System (INIS)

    Aydemir, A.Y.; Hazeltine, R.D.

    1986-09-01

    The sawtooth oscillations in the soft x-ray signals observed in tokamaks are associated with periodic changes in the central electron temperature, T/sub e/. Typically, a slow phase during which the central temperature slowly rises is followed by a fast drop in T/sub e/, associated with flattening of the central temperature. The time scale of the slow phase is determined by various transport processes such as ohmic heating. The resistive internal kink mode was invoked by Kadomtsev to explain the crash phase of the oscillations. Fast crash times observed in the large tokamaks are studied here, especially the fast crashes observed in JET. These sawtooth oscillations are characterized by the absence of any discrenible precursor oscillations, and a rapid collapse of the central temperature in about 100 microseconds. During the crash phase, the hot core region rapidly moves outward and is replaced by colder plasma. Then, this highly asymmetric state relaxes (in ∼100μsec) to a poloidally symmetric state in which a ring of hot plasma surrounds the colder core plasma, producing a hollow pressure profile

  13. Design and operation of remote maintenance systems in JET

    International Nuclear Information System (INIS)

    Raimondi, T.

    1987-01-01

    The JET tokamak is a joint European project aimed at proving the viability of nuclear fusion as a source of energy. A remote handling system is being developed for this large experimental facility. Force feedback servomanipulators and TV cameras are positioned at work locations by large transporters. Positioning and tele-operation are computer-assisted. Special tools are being devised to facilitate difficult tasks

  14. Application of dynamic response analysis to JET heat pulse data

    International Nuclear Information System (INIS)

    Griguoli, A.; Sips, A.C.C.

    1993-09-01

    The plasma dynamic response can be used to study transport processes in a tokamak plasma. A method has been developed for the application of dynamic response analysis to study perturbations away from the plasma equilibrium. In this report perturbations on the electron temperature following a sawtooth collapse in the center of the plasma are considered. The method has been used to find mathematical description of a series of heat pulses at the Joint European Torus project (JET). From the plasma dynamic response, the time constants which characterise the heat pulse are obtained. These time constants are compared to the transport coefficients found in previous analysis of the JET heat pulse data. Various methods are discussed for applying dynamic response analysis to JET heat pulse data. (author)

  15. X-ray crystal spectrometer upgrade for ITER-like wall experiments at JET

    Energy Technology Data Exchange (ETDEWEB)

    Shumack, A. E., E-mail: amy.shumack@ccfe.ac.uk [JET-EFDA, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); FOM Institute DIFFER, P.O. Box 1207, NL-3430 BE Nieuwegein (Netherlands); Rzadkiewicz, J. [National Centre for Nuclear Research, Andrzeja Sołtana 7, 05-400 Otwock (Poland); Chernyshova, M.; Czarski, T.; Karpinski, L. [Institute of Plasma Physics and Laser Microfusion, Hery 23, 01-497 Warsaw (Poland); Jakubowska, K. [Institute of Plasma Physics and Laser Microfusion, Hery 23, 01-497 Warsaw (Poland); Université Bordeaux, CNRS, CEA, CELIA, UMR 5107, F-33405 Talence (France); Scholz, M. [Institute of Nuclear Physics PAN, ul. Radzikowskiego 152, 31-342 Kraków (Poland); Byszuk, A.; Cieszewski, R.; Kasprowicz, G.; Pozniak, K.; Wojenski, A.; Zabolotny, W. [Institute of Electronic Systems, Warsaw University of Technology, 00-665 Warsaw (Poland); Dominik, W. [Faculty of Physics, Institute of Experimental Physics, Warsaw University, 00-681 Warsaw (Poland); Conway, N. J.; Dalley, S.; Tyrrell, S.; Zastrow, K.-D. [JET-EFDA, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Figueiredo, J. [EFDA-CSU, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Associação EURATOM/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Av Rovisco Pais, 1049-001 Lisbon (Portugal); and others

    2014-11-15

    The high resolution X-Ray crystal spectrometer at the JET tokamak has been upgraded with the main goal of measuring the tungsten impurity concentration. This is important for understanding impurity accumulation in the plasma after installation of the JET ITER-like wall (main chamber: Be, divertor: W). This contribution provides details of the upgraded spectrometer with a focus on the aspects important for spectral analysis and plasma parameter calculation. In particular, we describe the determination of the spectrometer sensitivity: important for impurity concentration determination.

  16. Development of 'popup' Langmuir probe system for the JET MkIIa divertor

    International Nuclear Information System (INIS)

    Davies, S.; Tellier, X.; Matthews, G.

    1999-01-01

    The successful operation of a 'popup' Langmuir probe system, which was installed in the JET MkIIa divertor, is described. The system utilises the ambient magnetic field in tokamak plasmas to act on a current carrying coil and pop up a rail containing Langmuir probes. Measurements were made using 'Pin-Plate' probes which, owing to their relatively large exposed area, are ideally suited for use with such a system. Details of the design, testing, measurements and potential applications of JET's 'popup' system are given. (author)

  17. FAR-TECH's Nanoparticle Plasma Jet System and its Application to Disruptions, Deep Fueling, and Diagnostics

    Science.gov (United States)

    Thompson, J. R.; Bogatu, I. N.; Galkin, S. A.; Kim, J. S.

    2012-10-01

    Hyper-velocity plasma jets have potential applications in tokamaks for disruption mitigation, deep fueling and diagnostics. Pulsed power based solid-state sources and plasma accelerators offer advantages of rapid response and mass delivery at high velocities. Fast response is critical for some disruption mitigation scenario needs, while high velocity is especially important for penetration into tokamak plasma and its confining magnetic field, as in the case of deep fueling. FAR-TECH is developing the capability of producing large-mass hyper-velocity plasma jets. The prototype solid-state source has produced: 1) >8.4 mg of H2 gas only, and 2) >25 mg of H2 and >180 mg of C60 in a H2/C60 gas mixture. Using a coaxial plasma gun coupled to the source, we have successfully demonstrated the acceleration of composite H/C60 plasma jets, with momentum as high as 0.6 g.km/s, and containing an estimated C60 mass of ˜75 mg. We present the status of FAR-TECH's nanoparticle plasma jet system and discuss its application to disruptions, deep fueling, and diagnostics. A new TiH2/C60 solid-state source capable of generating significantly higher quantities of H2 and C60 in <0.5 ms will be discussed.

  18. Continuous tokamaks

    International Nuclear Information System (INIS)

    Peng, Y.K.M.

    1978-04-01

    A tokamak configuration is proposed that permits the rapid replacement of a plasma discharge in a ''burn'' chamber by another one in a time scale much shorter than the elementary thermal time constant of the chamber first wall. With respect to the chamber, the effective duty cycle factor can thus be made arbitrarily close to unity minimizing the cyclic thermal stress in the first wall. At least one plasma discharge always exists in the new tokamak configuration, hence, a continuous tokamak. By incorporating adiabatic toroidal compression, configurations of continuous tokamak compressors are introduced. To operate continuous tokamaks, it is necessary to introduce the concept of mixed poloidal field coils, which spatially groups all the poloidal field coils into three sets, all contributing simultaneously to inducing the plasma current and maintaining the proper plasma shape and position. Preliminary numerical calculations of axisymmetric MHD equilibria in continuous tokamaks indicate the feasibility of their continued plasma operation. Advanced concepts of continuous tokamaks to reduce the topological complexity and to allow the burn plasma aspect ratio to decrease for increased beta are then suggested

  19. The rate of plasma heating by harmonic ion cyclotron waves in tokamaks

    International Nuclear Information System (INIS)

    Moslehi-Fard, M.; Sobhanian, S.; Solati-Kia, F.

    2002-01-01

    In tokamaks, the toroidal magnetic field, B φ , is due to the current in coils around plasma, and the poloidal magnetic field B p results from the plasma itself. Usually B φ p , and the combination of these two fields forms a nested set of toroidal magnetic surfaces. The equilibrium Grad-Shafranov equation is investigated and it is shown that the particle products of fusion with different pitch angles on these surfaces have different orbital shapes. In the JET tokamak, the α particles with pitch angle θ smaller than 54.8 deg are passing, those with θ between 54.8 deg and 65.1 deg have trapping-passing orbits but for θ greater than 65.1 deg the orbit has a banana form. Other tokamaks such as Alcator and ITER are also considered. The passing, trapping-passing and banana orbits in these tokamaks are traced. The results obtained from this calculation are analyzed. The wave damping has been investigated produced from interaction with particles, particularly α particles, and the rate of heating for l = 1 to 8 harmonics is plotted. The results of calculation show that heating at the fourth harmonic reaches a maximum. For higher harmonics, the heating does not change much from the fourth harmonic. (author)

  20. Spatial Resolution of the ECE for JET Typical Parameters

    International Nuclear Information System (INIS)

    Tribaldos, V.

    2000-01-01

    The purpose of this report is to obtain estimations of the spatial resolution of the electron cyclotron emission (ECE) phenomena for the typical plasmas found in JET tokamak. The analysis of the spatial resolution of the ECE is based on the underlying physical process of emission and a working definition is presented and discussed. In making these estimations a typical JET pulse is being analysed taking into account the magnetic configuration, the density and temperature profiles, obtained with the EFIT code and from the LIDAR diagnostic. Ray tracing simulations are performed for a Maxwellian plasma taking into account the antenna pattern. (Author) 5 refs

  1. Overview of the JET results

    Czech Academy of Sciences Publication Activity Database

    Romanelli, F.; Abhangi, M.; Abreu, P.; Aftanas, Milan; Afzal, M.; Aggarwal, K.M.; Aho-Mantila, L.; Ahonen, E.; Aints, M.; Airila, M.; Albanese, R.; Bílková, Petra; Cahyna, Pavel; Dejarnac, Renaud; Ďuran, Ivan; Fuchs, Vladimír; Horáček, Jan; Imríšek, M.; Janky, Filip; Ješko, Karol; Markovič, Tomáš; Mlynář, Jan; Peterka, Matěj; Petržílka, Václav; Tomeš, Matěj; Vondráček, Petr

    2015-01-01

    Roč. 55, č. 10 (2015), s. 104001 ISSN 0029-5515. [Fusion Energy Conference (FEC)/25./. St Petersburg, 13.10.2014-18.10.2014] Institutional support: RVO:61389021 Keywords : ITER-like wall * JET * tokamaks * magnetic confinement Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 4.040, year: 2015 http://iopscience.iop.org/article/10.1088/0029-5515/55/10/104001/meta;jsessionid=3FA2A9AC9BDFE6B4A43C77C9CF6C0DF0.c2.iopscience.cld.iop.org

  2. Runaway beam studies during disruptions at JET-ILW

    Czech Academy of Sciences Publication Activity Database

    Reux, C.; Plyusnin, V.; Alper, B.; Alves, D.; Bazylev, B.; Belonohy, E.; Brezinsek, S.; Decker, J.; Devaux, S.; de Vries, P.; Fil, A.; Gerasimov, S.; Lupelli, I.; Jachmich, S.; Khilkevitch, E.M.; Kiptily, V.; Koslowski, R.; Kruezi, U.; Lehnen, M.; Manzanares, A.; Mlynář, Jan; Nardon, E.; Nilsson, E.; Riccardo, V.; Saint-Laurent, F.; Shevelev, A.E.; Sozzi, C.

    2015-01-01

    Roč. 463, August (2015), s. 143-149 ISSN 0022-3115. [PLASMA-SURFACE INTERACTIONS 21: International Conference on Plasma-Surface Interactions in Controlled Fusion Devices. Kanazawa, 26.05.2014-30.05.2014] Institutional support: RVO:61389021 Keywords : tokamak * JET * runaway electrons * disruptions * ILW Subject RIV: JF - Nuclear Energetics OBOR OECD: Nuclear related engineering Impact factor: 2.199, year: 2015 http://www.sciencedirect.com/science/article/pii/S0022311514006850

  3. Confinement and stability in JET: recent results

    International Nuclear Information System (INIS)

    Campbell, D.J.

    1990-01-01

    The versatility of the JET device allows a wide range of tokamak operating regimes to be explored and plasmas bounded both by material limiters and by a magnetic separatrix have been investigated extensively. This has permitted the confinement and mhd stability properties of plasmas heated to temperatures above 10keV by neutral beam injection or ion cyclotron resonance heating to be studied in detail. The results of recent analyses of transport and confinement in the L- and H-mode regimes in JET are discussed and the properties of H-mode plasmas produced by both major forms of heating are compared. Several aspects of the mhd stability of such plasmas, particularly at high toroidal beta, β θ , and at the density limit, are reviewed. (author)

  4. The system architecture of the new JET Shape Controller

    International Nuclear Information System (INIS)

    Sartori, F.; Ambrosino, G.; Ariola, M.; Cenedese, A.; Crisanti, F.; Tommasi, G. De; Cullen, P. Mc; Piccolo, F.; Pironti, A.

    2005-01-01

    This paper describes the installation of the new JET Shape Controller System [M. Garribba, R. Litunovsky, P. Noll, S. Puppin, The new control scheme for the JET plasma position and current control system, in: Proceedings of the 15th SOFE Conference, Massachusetts, 1993, pp. 33-36; F. Sartori, A. Cenedese, Plasma position and current control management at JET, in: Proceedings of the 42nd IEEE Conference on Decision and Control, Maui, 2003] especially focusing on the addition of the Extreme Shape Controller [G. Ambrosino, et al., A new shape controller for extremely shaped plasmas in JET, Fusion Eng. Des. 66-68 (2003) 797-802]. The activity was performed by the JET Operator in co-operation with the ENEA-CREATE design team, and involved both changes in the hardware and system software of JET and tuning of the proposed Extreme Shape Controller (XSC) design to satisfy the practical requirements of tokamak operation. The application of 10 years experience of controller implementation and commissioning combined with a modern and efficient modelling and design methodology has allowed an unprecedented fast and easy commissioning of the new system

  5. Technical aspects of the joint JET-ISX-B beryllium limiter experiment

    International Nuclear Information System (INIS)

    Edmonds, P.H.; Dietz, K.J.; Mioduszewski, P.K.; Watson, R.D.; Emerson, L.C.; Gabbard, W.A.; Goodall, D.; Simpkins, J.E.; Yarber, J.L.

    1984-01-01

    An experiment has been performed on the Impurity Study Experiment (ISX-B) tokamak to test beryllium as a limiter material. Beryllium is an attractive candidate for a limiter and has been proposed for use in the Joint European Torus (JET) experiment. A temperature-controlled, segmented, beryllium top-rail limiter was located inside the plasma radius described by the existing titanium limiters. An extended set of diagnostics was added for measurement of scrapeoff and limiter parameters. These included visible and infrared monitoring systems, probes, and surface analysis experiments. Tokamak experiments included parameter surveys of both ohmically heated and neutral-beam-heated plasmas and an extended fluence test of the limiter

  6. Runaway electron beam generation and mitigation during disruptions at JET-ILW

    Czech Academy of Sciences Publication Activity Database

    Reux, C.; Plyusnin, V.; Alper, B.; Alves, D.; Bazylev, B.; Belonohy, E.; Boboc, A.; Brezinsek, S.; Coffey, I.; Decker, J.; Drewelow, P.; Devaux, S.; de Vries, P.C.; Fil, A.; Gerasimov, S.; Giacomelli, L.; Jachmich, S.; Khilkevitch, E.M.; Kiptily, V.; Koslowski, R.; Kruezi, U.; Lehnen, M.; Lupelli, I.; Lomas, P. J.; Manzanares, A.; Martin De Aguilera, A.; Matthews, G.F.; Mlynář, Jan; Nardon, E.; Nilsson, E.; Perez von Thun, C.; Riccardo, V.; Saint-Laurent, F.; Shevelev, A.E.; Sips, G.; Sozzi, C.

    2015-01-01

    Roč. 55, č. 9 (2015), 093013-093013 ISSN 0029-5515 Institutional support: RVO:61389021 Keywords : runaway electrons * disruptions * tokamak * JET * massive gas injection * disruption mitigation * runaway background plasma Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 4.040, year: 2015 http://iopscience.iop.org/article/10.1088/0029-5515/55/9/093013

  7. Runaway beam studies during disruptions at JET-ILW

    International Nuclear Information System (INIS)

    Reux, C.; Plyusnin, V.; Alper, B.; Alves, D.; Bazylev, B.; Belonohy, E.; Brezinsek, S.; Decker, J.; Devaux, S.; Vries, P. de; Fil, A.

    2015-01-01

    Highlights: • Runaway electrons (RE) have been obtained at JET-ILW using massive argon injection. • The runaway electron domain entry points are similar between JET-C and JET-ILW. • Inside the runaway electron domain, higher RE currents are observed with JET-ILW. • RE impact has been observed without material melting up to 100 kA RE current. • Heat deposition of 2 ± 1 mm is confirmed by measurements and simulations. - Abstract: Runaway electrons (RE) during disruptions are a concern for future tokamaks including ITER with its metallic wall. Although RE are rare in spontaneous disruptions with the JET ITER-like Wall (JET-ILW), RE beams up to 380 kA were obtained using massive injection (MGI) of argon in JET-ILW divertor discharges. Entry points into the RE domain defined by operational parameters (toroidal field, argon fraction in MGI) are unchanged but higher RE currents have been obtained inside the JET-ILW MGI-generated RE domain when compared to JET-C. This might be due to the influence of the metallic wall on the current quench plasma. Temperatures of 900 °C have been observed following RE impacts on beryllium tiles. Heat deposition depth of ∼2 mm has to be assumed to match the tile cooling time. 3D simulations of the RE energy deposition using the ENDEP/MEMOS codes show that material melting is unlikely with 100 kA RE beams

  8. Runaway beam studies during disruptions at JET-ILW

    Energy Technology Data Exchange (ETDEWEB)

    Reux, C., E-mail: cedric.reux@cea.fr [JET-EFDA, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); Plyusnin, V. [JET-EFDA, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Instituto de Plasmas e Fuso Nuclear, Instituto Superior Tcnico, Universidade de Lisboa, Lisboa (Portugal); Alper, B. [JET-EFDA, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Alves, D. [JET-EFDA, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Instituto de Plasmas e Fuso Nuclear, Instituto Superior Tcnico, Universidade de Lisboa, Lisboa (Portugal); Bazylev, B. [JET-EFDA, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Institut für Hochleistungsimpuls und Mikrowellentechnik, Karlsruhe Institute of Technology, Campus Nord, 76021 Karlsruhe (Germany); Belonohy, E. [JET-EFDA, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); EFDA-CSU, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Brezinsek, S. [JET-EFDA, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Forschungszentrum Jülich GmbH, Institut für Energie-und Klimaforschung-Plasmaphysik, 52425 Jülich (Germany); Decker, J. [JET-EFDA, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); Devaux, S. [JET-EFDA, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Vries, P. de [JET-EFDA, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); ITER Organization, Route de Vinon sur Verdon, 13115 St Paul Lez Durance (France); Fil, A. [JET-EFDA, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); and others

    2015-08-15

    Highlights: • Runaway electrons (RE) have been obtained at JET-ILW using massive argon injection. • The runaway electron domain entry points are similar between JET-C and JET-ILW. • Inside the runaway electron domain, higher RE currents are observed with JET-ILW. • RE impact has been observed without material melting up to 100 kA RE current. • Heat deposition of 2 ± 1 mm is confirmed by measurements and simulations. - Abstract: Runaway electrons (RE) during disruptions are a concern for future tokamaks including ITER with its metallic wall. Although RE are rare in spontaneous disruptions with the JET ITER-like Wall (JET-ILW), RE beams up to 380 kA were obtained using massive injection (MGI) of argon in JET-ILW divertor discharges. Entry points into the RE domain defined by operational parameters (toroidal field, argon fraction in MGI) are unchanged but higher RE currents have been obtained inside the JET-ILW MGI-generated RE domain when compared to JET-C. This might be due to the influence of the metallic wall on the current quench plasma. Temperatures of 900 °C have been observed following RE impacts on beryllium tiles. Heat deposition depth of ∼2 mm has to be assumed to match the tile cooling time. 3D simulations of the RE energy deposition using the ENDEP/MEMOS codes show that material melting is unlikely with 100 kA RE beams.

  9. ICRF Mode Conversion Current Drive for Plasma Stability Control in Tokamaks

    International Nuclear Information System (INIS)

    Grekov, D.; Kock, R.; Lyssoivan, A.; Noterdaeme, J. M.; Ongena, J.

    2007-01-01

    There is a substantial incentive for the International Thermonuclear Experimental Reactor (ITER) to operate at the highest attainable beta (plasma pressure normalized to magnetic pressure), a point emphasized by requirements of attractive economics in a reactor. Recent experiments aiming at stationary high beta discharges in tokamak plasmas have shown that maximum achievable beta value is often limited by the onset of instabilities at rational magnetic surfaces (neoclassical tearing modes). So, methods of effective control of these instabilities have to be developed. One possible way for neoclassical tearing modes control is an external current drive in the island to locally replace the missing bootstrap current and thus to suppress the instability. Also, a significant control of the sawtooth behaviour was demonstrated when the magnetic shear was modified by driven current at the magnetic surface where safety factor equals to 1. In the ion cyclotron range of frequencies (ICRF), the mode conversion regime can be used to drive the local external current near the position of the fast-to-slow wave conversion layer, thus providing an efficient means of plasma stability control. The slow wave energy is effectively absorbed in the vicinity of mode conversion layer by electrons with such parallel to confining magnetic field velocities that the Landau resonance condition is satisfied. For parameters of present day tokamaks and for ITER parameters the slow wave phase velocity is rather low, so the large ratio of momentum to energy content would yield high current drive efficiency. In order to achieve noticeable current drive effect, it is necessary to create asymmetry in the ICRF power absorption between top and bottom parts of the plasma minor cross-section. Such asymmetric electron heating may be realized using: - shifted from the torus midplane ICRF antenna in TEXTOR tokamak; - plasma displacement in vertical direction that is feasible in ASDEX-Upgrade; - the

  10. Modeling of noble gas injection into tokamak plasmas

    International Nuclear Information System (INIS)

    Morozov, D.Kh.; Yurchenko, E.I.; Lukash, V.E.; Baronova, E.O.; Rozhansky, V.A.; Senichenkov, I.Yu.; Veselova, I.Yu.; Schneider, R.

    2005-01-01

    Noble gas injection for mitigation of the disruption in DIII-D is simulated. The simulation of the first two stages is performed: of the neutral gas jet penetration through the background plasmas, and of the thermal quench. In order to simulate the first stage the 1.5-dimensional numerical code LLP with improved radiation model for noble gas is used. It is demonstrated that the jet remains mainly neutral and thus is able to penetrate to the central region of the tokamak in accordance with experimental observations. Plasma cooling at this stage is provided by the energy exchange with the jet. The radiation is relatively small, and the plasma thermal energy is spent mainly on the jet expansion. The magnetic surfaces in contact with the jet are cooled significantly. The cooling front propagates towards the plasma center. The simulations of the plasma column dynamics in the presence of moving jet is performed by means of the free boundary transport modeling DINA code. It has been shown that the cooling front is accompanied by strongly localized 'shark fin-like' perturbation in toroidal current density profile. After few milliseconds the jet (together with the current perturbation) achieves the region where safety factor is slightly higher than unity and a new type of the non-local kink mode develops. The unstable kink perturbation is non-resonant for any magnetic surface, both inside the plasma column, and in the vacuum space. The mode disturbs mainly the core region. The growth time of the 'shark fin-like' mode is higher than the Alfven time by a factor of 100 for DIII-D parameters. Hence, the simulation describes the DIII-D experimental results, at least, qualitatively. (author)

  11. Thresholds of ion turbulence in tokamaks

    International Nuclear Information System (INIS)

    Garbet, X.; Laurent, L.; Mourgues, F.; Roubin, J.P.; Samain, A.; Zou, X.L.

    1991-01-01

    The linear thresholds of ionic turbulence are numerically calculated for the Tokamaks JET and TORE SUPRA. It is proved that the stability domain at η i >0 is determined by trapped ion modes and is characterized by η i ≥1 and a threshold L Ti /R of order (0.2/0.3)/(1+T i /T e ). The latter value is significantly smaller than what has been previously predicted. Experimental temperature profiles in heated discharges are usually marginal with respect to this criterium. It is also shown that the eigenmodes are low frequency, low wavenumber ballooned modes, which may produce a very large transport once the threshold ion temperature gradient is reached

  12. Development of pop-up Langmuir probe system for the JET MkIIa divertor

    International Nuclear Information System (INIS)

    Davies, S.J.; Tellier, X.; Matthews, G.F.; Wilson, C.H.

    1999-01-01

    The successful operation of a pop-up Langmuir probe system, which was installed in the JET MkIIa divertor, is described. The system utilises the ambient magnetic field in tokamak plasmas to act on a current carrying coil and pop up a rail containing Langmuir probes. Measurements were made using pin-plate probes which, owing to their relatively large exposed area, are ideally suited for use with such a system. Details of the design, testing, measurements and potential applications of JET's pop-up system are given. (orig.)

  13. Real-time control of current and pressure profiles in tokamak plasmas

    International Nuclear Information System (INIS)

    Laborde, L.

    2005-12-01

    Recent progress in the field of 'advanced tokamak scenarios' prefigure the operation regime of a future thermonuclear fusion power plant. Compared to the reference regime, these scenarios offer a longer plasma confinement time thanks to increased magnetohydrodynamic stability and to a better particle and energy confinement through a reduction of plasma turbulence. This should give access to comparable fusion performances at reduced plasma current and could lead to a steady state fusion reactor since the plasma current could be entirely generated non-inductively. Access to this kind of regime is provided by the existence of an internal transport barrier, linked to the current profile evolution in the plasma, which leads to steep temperature and pressure profiles. The comparison between heat transport simulations and experiments allowed the nature of the barriers to be better understood as a region of strongly reduced turbulence. Thus, the control of this barrier in a stationary manner would be a remarkable progress, in particular in view of the experimental reactor ITER. The Tore Supra and JET tokamaks, based in France and in the United Kingdom, constitute ideal instruments for such experiments: the first one allows stationary plasmas to be maintained during several minutes whereas the second one provides unique fusion performances. In Tore Supra, real-time control experiments have been accomplished where the current profile width and the pressure profile gradient were controlled in a stationary manner using heating and current drive systems as actuators. In the JET tokamak, the determination of an empirical static model of the plasma allowed the current and pressure profiles to be simultaneously controlled and so an internal transport barrier to be sustained. Finally, the identification of a dynamic model of the plasma led to the definition of a new controller capable, in principle, of a more efficient control. (author)

  14. Electrical conductivity in tokamaks and extended neoclassical theory

    International Nuclear Information System (INIS)

    Segre, S.E.; Zanza, V.

    1992-01-01

    The electrical conductivity measurements reported from various tokamaks (D-III, PLT, TEXT, ASDEX, JT-60, TEXTOR, JET, TFTR) and compared with the usual neoclassical theory are here also compared with the extended neoclassical theory where the electron-electron collision rate is anomalous while the electron-ion collision rate remains Coulombian. It is found that, out of the 14 experiments considered, three are consistent with both the neoclassical and the extended neoclassical theories, four are consistent only with the extended neoclassical theory, and four are consistent with the neoclassical theory and also, within the experimental errors, not inconsistent with the extended neoclassical theory; the remaining three experiments appear to be incompatible with both theories. It is concluded that the extended neoclassical theory is in better agreement with conductivity experiments than the conventional neoclassical theory and, indeed, the extended theory is a serious candidate for explaining tokamak behaviour, since it accommodates naturally an anomalous electron thermal transport, which the conventional neoclassical theory is unable to do. (author). 31 refs, 1 fig

  15. VH mode accessibility and global H-mode properties in previous and present JET configurations

    Energy Technology Data Exchange (ETDEWEB)

    Jones, T T.C.; Ali-Arshad, S; Bures, M; Christiansen, J P; Esch, H P.L. de; Fishpool, G; Jarvis, O N; Koenig, R; Lawson, K D; Lomas, P J; Marcus, F B; Sartori, R; Schunke, B; Smeulders, P; Stork, D; Taroni, A; Thomas, P R; Thomsen, K [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking

    1994-07-01

    In JET VH modes, there is a distinct confinement transition following the cessation of ELMs, observed in a wide variety of tokamak operating conditions, using both NBI and ICRF heating methods. Important factors which influence VH mode accessibility such as magnetic configuration and vessel conditions have been identified. The new JET pumped divertor configuration has much improved plasma shaping control and power and particle exhaust capability and should permit exploitation of plasmas with VH confinement properties over an even wider range of operating regimes, particularly at high plasma current; first H-modes have been obtained in the 1994 JET operating period and initial results are reported. (authors). 7 refs., 6 figs.

  16. Effect of ripple-induced transport on H-mode performance in tokamaks

    International Nuclear Information System (INIS)

    Parail, V.; Vries, P. de; Lonnroth, J.; Kiviniemi, T.; Johnson, T.; Loarte, A.; Saibene, G.; Hatae, T.; Kamada, Y.; Konovalov, S.; Oyama, N.; Shinohara, K.; Tobita, K.; Urano, H.

    2005-01-01

    A number of experiments have shown that ripple-induced transport influences performance of ELMy H-modes in the tokamak. A noticeable difference in confinement, ELM frequency and amplitude was found between JET (with ripple amplitude δ∼0.1%) and JT-60U (with δ∼1%) in otherwise identical discharges. It was previously shown in JET experiments with enhanced ripple that a gradual increase in the ripple amplitude first leads to a modest improvement in plasma confinement, which is followed by the degradation of edge pedestal and further transition to the L-mode regime if δ increases further. The DIII-D team recently reported a marginal increase in confinement in experiments with an edge transport enhanced by the externally driven resonant magnetic perturbation. Numerical predictive modelling of the dynamics of ELMy H-mode JET plasma relevant to a JET/JT-60U similarity experiment has been conducted taking into account ripple-induced ion transport, which was computed using the orbit following code ASCOT. This predictive modelling reveals that, depending on plasma parameters, ripple amplitude and localisation (the latter depending on the toroidal coil design), this additional transport can either improve global plasma confinement or reduce it. These controlled ripple losses might be used as an effective tool for ELM mitigation and may provide an explanation for the difference between JET and JT-60U observed in the similarity experiments. A detailed comparison between ripple- induced transport and the alternative method of ELM mitigation by an externally driven edge magnetic perturbation is discussed. The fact that ripple losses mainly increase ion transport, while a stochastic magnetic layer increases electron transport indicates that it might be beneficial to use a combination of both methods in future experiments. This work was funded partly by the United Kingdom Engineering and Physical Sciences Research Council and by the European Communities under the contract of

  17. Tokamak Systems Code

    International Nuclear Information System (INIS)

    Reid, R.L.; Barrett, R.J.; Brown, T.G.

    1985-03-01

    The FEDC Tokamak Systems Code calculates tokamak performance, cost, and configuration as a function of plasma engineering parameters. This version of the code models experimental tokamaks. It does not currently consider tokamak configurations that generate electrical power or incorporate breeding blankets. The code has a modular (or subroutine) structure to allow independent modeling for each major tokamak component or system. A primary benefit of modularization is that a component module may be updated without disturbing the remainder of the systems code as long as the imput to or output from the module remains unchanged

  18. Sawtooth driven particle transport in tokamak plasmas

    International Nuclear Information System (INIS)

    Nicolas, T.

    2013-01-01

    The radial transport of particles in tokamaks is one of the most stringent issues faced by the magnetic confinement fusion community, because the fusion power is proportional to the square of the pressure, and also because accumulation of heavy impurities in the core leads to important power losses which can lead to a 'radiative collapse'. Sawteeth and the associated periodic redistribution of the core quantities can significantly impact the radial transport of electrons and impurities. In this thesis, we perform numerical simulations of sawteeth using a nonlinear tridimensional magnetohydrodynamic code called XTOR-2F to study the particle transport induced by sawtooth crashes. We show that the code recovers, after the crash, the fine structures of electron density that are observed with fast-sweeping reflectometry on the JET and TS tokamaks. The presence of these structure may indicate a low efficiency of the sawtooth in expelling the impurities from the core. However, applying the same code to impurity profiles, we show that the redistribution is quantitatively similar to that predicted by Kadomtsev's model, which could not be predicted a priori. Hence finally the sawtooth flushing is efficient in expelling impurities from the core. (author) [fr

  19. Calibration of the JET neutron yield monitors using the delayed neutron counting technique

    International Nuclear Information System (INIS)

    van Belle, P.; Jarvis, O.N.; Sadler, G.; de Leeuw, S.; D'Hondt, P.; Pillon, M.

    1990-01-01

    The time-resolved neutron yield is routinely measured on the JET tokamak using a set of fission chambers. At present, the preferred technique is to employ activation reactions to determine the neutron fluence at a well-chosen position and to relate the measured fluence to the total neutron emission by means of neutron transport calculations. The delayed neutron counting method is a particularly convenient method of performing the activation measurement and the fission cross sections are accurately known. This paper outlines the measurement technique as used on JET

  20. Optimization of ICRH for core impurity control in JET-ILW

    Czech Academy of Sciences Publication Activity Database

    Lerche, E.; Goniche, M.; Jacquet, P.; Van Eester, D.; Bobkov, V.; Colas, L.; Giroud, C.; Monakhov, I.; Casson, F.J.; Rimini, F.; Angioni, C.; Baruzzo, M.; Blackman, T.; Brezinsek, S.; Brix, M.; Czarnecka, A.; Crombé, K.; Challis, C.; Dumont, R.; Eriksson, J.; Fedorczak, N.; Graham, M.; Graves, J.P.; Gorini, G.; Hobirk, J.; Joffrin, E.; Johnson, T.; Kazakov, Y.; Kiptily, V.; Krivska, A.; Lennholm, M.; Lomas, P.; Maggi, C.; Mantica, P.; Mathews, G.; Mayoral, M.-L.; Meneses, L.; Mlynář, Jan; Monier-Garbet, P.; Nave, M.F.; Noble, C.; Nocente, M.; Nunes, I.; Ongena, J.; Petravich, G.; Petržílka, Václav; Pütterich, T.; Reich, M.; Santala, M.; Solano, E.R.; Shaw, A.; Sips, G.; Stamp, M.; Tardocchi, M.; Tsalas, M.; Valisa, M.

    2016-01-01

    Roč. 56, č. 3 (2016), s. 036022 ISSN 0029-5515 EU Projects: European Commission(XE) 633053 - EUROfusion Institutional support: RVO:61389021 Keywords : ICRF heating * tokamak * ITER-like wall * JET Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 3.307, year: 2016 http://iopscience.iop.org/article/10.1088/0029-5515/56/3/036022

  1. Comparing scrape-off layer and divertor physics in JET pure He and D discharges

    NARCIS (Netherlands)

    Pitts, R.A.; Andrew, P.; Andrew, Y.; Becoulet, M.; Coffey, I.; Coster, D.; McDonald, D. C.; Eich, T.; Erents, S.K.; Fenstermacher, M.E.; Fundamenski, W.; Haas, G.; Hermann, A.; Hidalgo, C.; Hillis, D.; Huber, A.; Ingesson, L. C.; Jachmich, S.; Kallenbach, A.; Korotkov, A.; Lawson, K.; Lomas, P.; Loarer, T.; Loarte, A.; Matthews, G. F.; McCracken, G.; Meigs, A.; Mertens, P.; O' Mullane, M.; Phillipps, V.; Porter, G.; Pospieszczyk, A.; Rapp, J.; Reiter, D.; Riccardo, V.; Saibene, G.; Sartori, R.; Stamp, M. F.; Tsitrone, E.; Wischmeier, W.; Gafert, J.

    2003-01-01

    Though helium plasmas are one option for the low activation phase of ITER, little effort has thus far been devoted to studying them in a large, diverted tokamak. A recent campaign on JET has therefore sought to address some of the important questions related to helium operation (He concentrations

  2. ITER-like current ramps in JET with ILW: experiments, modelling and consequences for ITER

    Czech Academy of Sciences Publication Activity Database

    Hogeweij, G.M.D.; Calabrò, G.; Sips, A.C.C.; Maggi, C.F.; De Tommasi, G.M.; Joffrin, E.; Loarte, A.; Maviglia, F.; Mlynář, Jan; Rimini, F.G.; Pütterich, T.

    2015-01-01

    Roč. 55, č. 1 (2015), 013009-013009 ISSN 0029-5515 Institutional support: RVO:61389021 Keywords : tokamak * ramp-up * JET * ITER Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 4.040, year: 2015 http://iopscience.iop.org/article/10.1088/0029-5515/55/1/013009#metrics

  3. Stationary Flowing Liquid Lithium (SFLiLi) systems for tokamaks

    Science.gov (United States)

    Zakharov, Leonid; Gentile, Charles; Roquemore, Lane

    2013-10-01

    The present approach to magnetic fusion which relies on high recycling plasma-wall interaction has exhausted itself at the level of TFTR, JET, JT-60 devices with no realistic path to the burning plasma. Instead, magnetic fusion needs a return to its original idea of insulation of the plasma from the wall, which was the dominant approach in the 1970s and upon implementations has a clear path to the DEMO device with PDT ~= 100 MW and Qelectric > 1 . The SFLiLi systems of this talk is the technology tool for implementation of the guiding idea of magnetic fusion. It utilizes the unique properties of flowing LiLi to pump plasma particles and, thus, insulate plasma from the walls. The necessary flow rate, ~= 1 g3/s, is very small, thus, making the use of lithium practical and consistent with safety requirements. The talk describes how chemical activity of LiLi, which is the major technology challenge of using LiLi in tokamaks, is addressed by SFLiLi systems at the level of already performed (HT-7) experiment, and in ongoing implementations for a prototype of SFLiLi for tokamak divertors and the mid-plane limiter for EAST tokamak (to be tested in the next experimental campaign). This work is supported by US DoE contract No. DE-AC02-09-CH11466.

  4. Transitions in boronlike Ni XXIV, Ge XXVIII, Kr XXXII and Mo XXXVIII and fluorinelike Zr XXXII and Mo XXXIV, observed in the JET tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Myrnaes, R [Dept. of Physics, Univ. of Lund (Sweden); Jupen, C [Dept. of Physics, Univ. of Lund (Sweden); Miecznik, G [Dept. of Physics, Univ. of Lund (Sweden); Martinson, I [Dept. of Physics, Univ. of Lund (Sweden); Denne-Hinnov, B [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking

    1994-01-01

    Spectra of highly ionized Ni, Ge, Kr, Zr and Mo obtained from the JET tokamak have been studied. In total 20 new lines have been classified as n = 2, [Delta]n = 0 transitions in B-like and F-like ions. Among the identified lines are M1 transitions within the 2s[sup 2]2p[sup 5] [sup 2]P ground term of F-like Zr and Mo and within the 2s[sup 2]2p [sup 2]P ground term of B-like Mo. Furthermore, for B-like Ni, Kr and Mo, the 2s2p[sup 2] [sup 4]P[sub 1/2] and [sup 4]P[sub 5/2] levels, which decay by spin-forbidden transitions, have been found. From the observed wavelengths 20 new energy levels were determined. The experiments have been complemented with multiconfiguration Dirac-Fock (MCDF) calculations and semiempirical analyses of transition energies in the B I and F I isoelectronic sequences. (orig.).

  5. PPPL tokamak program

    International Nuclear Information System (INIS)

    Furth, H.P.

    1984-10-01

    The economic prospects of the tokamak are reviewed briefly and found to be favorable - if the size of ignited tokamak plasmas can be kept small and appropriate auxiliary systems can be developed. The main objectives of the Princeton Plasma Physics Laboratory tokamak program are: (1) exploration of the physics of high-temperature toroidal confinement, in TFTR; (2) maximization of the tokamak beta value, in PBX; (3) development of reactor-relevant rf techniques, in PLT

  6. Automatic location of disruption times in JET

    Science.gov (United States)

    Moreno, R.; Vega, J.; Murari, A.

    2014-11-01

    The loss of stability and confinement in tokamak plasmas can induce critical events known as disruptions. Disruptions produce strong electromagnetic forces and thermal loads which can damage fundamental components of the devices. Determining the disruption time is extremely important for various disruption studies: theoretical models, physics-driven models, or disruption predictors. In JET, during the experimental campaigns with the JET-C (Carbon Fiber Composite) wall, a common criterion to determine the disruption time consisted of locating the time of the thermal quench. However, with the metallic ITER-like wall (JET-ILW), this criterion is usually not valid. Several thermal quenches may occur previous to the current quench but the temperature recovers. Therefore, a new criterion has to be defined. A possibility is to use the start of the current quench as disruption time. This work describes the implementation of an automatic data processing method to estimate the disruption time according to this new definition. This automatic determination allows both reducing human efforts to locate the disruption times and standardizing the estimates (with the benefit of being less vulnerable to human errors).

  7. Automatic location of disruption times in JET.

    Science.gov (United States)

    Moreno, R; Vega, J; Murari, A

    2014-11-01

    The loss of stability and confinement in tokamak plasmas can induce critical events known as disruptions. Disruptions produce strong electromagnetic forces and thermal loads which can damage fundamental components of the devices. Determining the disruption time is extremely important for various disruption studies: theoretical models, physics-driven models, or disruption predictors. In JET, during the experimental campaigns with the JET-C (Carbon Fiber Composite) wall, a common criterion to determine the disruption time consisted of locating the time of the thermal quench. However, with the metallic ITER-like wall (JET-ILW), this criterion is usually not valid. Several thermal quenches may occur previous to the current quench but the temperature recovers. Therefore, a new criterion has to be defined. A possibility is to use the start of the current quench as disruption time. This work describes the implementation of an automatic data processing method to estimate the disruption time according to this new definition. This automatic determination allows both reducing human efforts to locate the disruption times and standardizing the estimates (with the benefit of being less vulnerable to human errors).

  8. Interpretation of heat and density pulse propagation in tokamaks

    International Nuclear Information System (INIS)

    Sips, A.C.C.; Costley, A.E.; O'Rourke, J.O.

    1991-01-01

    This paper addresses two key issues in current research on sawtooth induced heat and density pulse measurements in Tokamaks and their interpretation. First, heat and density pulses in JET and TXT show different qualitative behaviour implying substantially different transport coefficients. Second, a new description of the heat pulse has been used to describe measurements cannot be simulated with the widely used diffusive model. In this paper, we show that consistency between all these measurements can be obtained assuming a diffusive propagation for the heat and density pulses and using linearised coupled transport equations. (author) 6 refs., 5 figs

  9. Auxiliary radiofrequency heating of tokamaks, Task 3

    International Nuclear Information System (INIS)

    Scharer, J.E.

    1991-07-01

    The research performed under this grant during the past three years has been concentrated on the following several key tokamak ICRF (Ion Cyclotron Range of Frequencies) coupling and heating issues: efficient coupling during the L- to H-mode transition by analysis and computer simulation of ICRF antennas edge plasma profiles; analysis of both dielectric-filled waveguide and coil ICRF antenna coupling to plasma edge profiles; benchmarking the codes to compare with current JET, D-IIID and ASDEX experimental results; ICRF full-wave field solutions, power conservation and heating analyses; and the effects of fusion alpha particle or ion tail populations on the ICRF absorption. Research progress, publications, and conference and workshop presentations are summarized in this report. 15 refs

  10. Magneto-hydro-dynamic simulation of Edge-Localised-Modes in tokamaks

    International Nuclear Information System (INIS)

    Pamela, S.

    2010-01-01

    In order to produce energy from fusion reactions in a tokamak, the plasma must reach temperatures higher than that of our sun. The operation regime called H-mode enables one to acquire a plasma confinement close to fusion conditions. Due to the formation of a transport barrier at the plasma edge, turbulent transport is reduced, and the total plasma pressure increases, resulting in a strong pressure gradient at the edge. If this pressure gradient, localised at the plasma-vacuum boundary, becomes too steep, a magneto-hydro-dynamic instability is triggered and part of the plasma pressure is lost. This instability, hence called Edge-Localised-Mode, provokes large heat fluxes on some of the plasma-facing components of the machine, which could set operational limits for a tokamak the size of ITER. In order to understand this instability, and to determine the non-linear mechanisms behind the ELMs, the JOREK code is used. The work presented in this thesis is based on MHD simulations of ballooning modes (responsible for ELMs) with the JOREK code. At first, simulations are done for standard plasmas, inspired of experimental machines. In particular, the plasma rotation at equilibrium, in the region of the edge pressure gradient, is studied in order to obtain an analysis of the effects that such a rotation can have on the linear stability of ELMs and on their non-linear evolution. Then, as a second step, simulations are applied to plasmas of the experimental tokamaks JET and MAST (England). This permits the direct comparison of simulation results with experimental observations, with the main goal of improving our global understanding of ELMs. Adding to this physics aspect, the confrontation of the JOREK code with diagnostics of JET and MAST brings to a validation of simulations, which should prove that the simulations which were obtained do correspond to ELM instabilities. This first step towards the validation of the code is crucial concerning the simulation of ELMs in ITER

  11. The JET neutron emission profile monitor

    International Nuclear Information System (INIS)

    Adams, J.M.; Syme, D.B.; Watkins, N.; Jarvis, O.N.; Sadler, G.J.

    1993-01-01

    This paper provides a technical description of the neutron emission profile monitor as used routinely at the Joint European Torus (JET), and includes representative examples of its operational capabilities. The primary function of this instrument is to measure the neutron emission as a function of both position and time in a poloidal (vertical along major radius) section through the torus. For the first time the spatially localised effects of sawteeth (magnetic relaxation phenomena) have been observed using a neutron diagnostic. The total (global) neutron emission can be obtained from the profile monitor data by performing a volume integral over the plasma; the absolute neutron emission rates agree with those obtained from the JET time-resolved neutron monitor to within ±15%. This was the first such instrument routinely in use on any tokamak. It provides unique data which are independent of all other diagnostic measurements. (orig.)

  12. Upgrade of the TCV tokamak, first phase: Neutral beam heating system

    Energy Technology Data Exchange (ETDEWEB)

    Karpushov, Alexander N., E-mail: alexander.karpushov@epfl.ch [Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, CH-1015 Lausanne (Switzerland); Alberti, Stefano; Chavan, René [Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, CH-1015 Lausanne (Switzerland); Davydenko, Vladimir I. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Duval, Basil P. [Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, CH-1015 Lausanne (Switzerland); Ivanov, Alexander A. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Fasel, Damien; Fasoli, Ambrogio [Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, CH-1015 Lausanne (Switzerland); Gorbovsky, Aleksander I. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Goodman, Timothy [Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, CH-1015 Lausanne (Switzerland); Kolmogorov, Vyacheslav V. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Martin, Yves; Sauter, Olivier [Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, CH-1015 Lausanne (Switzerland); Sorokin, Aleksey V. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); and others

    2015-10-15

    Highlights: • Widening the parameter range of reactor relevant regimes on the TCV tokamak. • Installation of 1 MW, 30 keV neutral beam, direct ion heating, access to T{sub i}/T{sub e} ≥ 1. • ASTRA simulation of plasma response to NB and EC heating in different regimes. • Specific low divergency neutral beam injector with tunable beam power and energy. - Abstract: Experiments on TCV are designed to complement the work at large integrated tokamak facilities (such as JET) to provide a stepwise approach to extrapolation to ITER and DEMO in areas where medium-size tokamaks can often exploit their experimental capabilities and flexibility. Improving the understanding and control requirements of burning plasmas is a major scientific challenge, requiring access to plasma regimes and configurations with high normalized plasma pressure and a wide range of ion to electron temperature ratios, including T{sub e}/T{sub i} ∼ 1. These conditions will be explored by adding a 1 MW neutral heating beam to TCV's auxiliary for direct ion heating (2015) and increasing the ECH power injected in X-mode at the third harmonic (2 MW in 2015–2016). The manufacturing of the neutral beam injector was launched in 2014.

  13. Implementation of a new Disruption Mitigation System into the control system of JET

    Energy Technology Data Exchange (ETDEWEB)

    Jachmich, Stefan, E-mail: s.jachmich@fz-juelich.de [Laboratory for Plasma Physics, Ecole Royale Militaire/Koninklijke Militaire School, B-1000 Brussels (Belgium); Kruezi, Uron; Card, Peter; Deakin, Kieron; Kinna, David [Culham Centre for Fusion Energy, Abingdon, Oxon OX14 3DB (United Kingdom); Koslowski, Hans Rudolf; Lambertz, Horst Toni [Forschungszentrum Jülich GmbH, IEK-4, 52425 Jülich (Germany); Lehnen, Michael [ITER Organization, Route de Vinon-sur-Verdon, CS90046, 13067 St Paul Lez Durance Cedex (France)

    2015-10-15

    Highlights: • A new Disruption Mitigation System based on Massive Gas Injection has been installed at JET. • The control of the attached gas handling system had to be integrated into the JET-operation. • An interlock system has been built to cope with the interaction of the DMS with other auxiliary systems. • The system has been commissioned and first example of DMS used to ameliorate a disruption are shown. - Abstract: A new Disruption Mitigation System (DMS) based on Massive Gas Injections (MGI) has been installed at the JET-tokamak. The key component of this system is a fast eddy current driven valve, which is capable of injecting up to 4.6 × 10{sup −3} MPa m{sup 3} in less than 5 ms. Along with this valve a new gas handling system has been installed, whose control had to be integrated into the JET-operation. The operation of the DMS requires interaction with several other systems. Although Massive Gas Injections are used to ameliorate potentially severe damage to the tokamak plant and plasma facing components caused by disruptions, they introduce a high risk for example to auxiliary heating systems or diagnostics, which could be damaged by high vacuum pressures. In addition to this, the presence of high pressure (of noble and flammable gases) in combination with high voltages represents a risk not only to the actual DMS plant itself (in case of a failure) but also to personnel in the vicinity. These varieties of risks have been addressed and are described in this article.

  14. Jet supercooling and molecular jet spectroscopy

    International Nuclear Information System (INIS)

    Wharton, L.; Levy, D.

    1979-01-01

    The marriage of the laser and the seeded supersonic jet has generated a family of new optical spectroscopic results. We shall discuss the essential features of the technique and some results. The results will include structural and dynamical views of NO 2 , NaAr, and I 2 -noble gas complexes. The extension of the method to heavier systems is illustrated with free base phthalocyanine

  15. Experimental tests of confinement scale invariance on JET, DIIID, ASDEX Upgrade and CMOD

    International Nuclear Information System (INIS)

    Christiansen, J.P.; Cordey, J.G.; Budny, R.

    2001-01-01

    An international collaboration between JET, DIIID, AUG and CMOD has resulted in four sets of Tokamak discharges which are approximately identical as regards a set of dimensionless plasma variables. The data demonstrates some measure of scale invariance of local and global confinement but a more accurate matching of scaled density, power etc. is required to make firmer conclusions. (author)

  16. Tokamak engineering mechanics

    International Nuclear Information System (INIS)

    Song, Yuntao; Wu, Weiyue; Du, Shijun

    2014-01-01

    Provides a systematic introduction to tokamaks in engineering mechanics. Includes design guides based on full mechanical analysis, which makes it possible to accurately predict load capacity and temperature increases. Presents comprehensive information on important design factors involving materials. Covers the latest advances in and up-to-date references on tokamak devices. Numerous examples reinforce the understanding of concepts and provide procedures for design. Tokamak Engineering Mechanics offers concise and thorough coverage of engineering mechanics theory and application for tokamaks, and the material is reinforced by numerous examples. Chapter topics include general principles, static mechanics, dynamic mechanics, thermal fluid mechanics and multiphysics structural mechanics of tokamak structure analysis. The theoretical principle of the design and the methods of the analysis for various components and load conditions are presented, while the latest engineering technologies are also introduced. The book will provide readers involved in the study of mechanical/fusion engineering with a general understanding of tokamak engineering mechanics.

  17. Tokamak concept innovations

    International Nuclear Information System (INIS)

    1986-04-01

    This document contains the results of the IAEA Specialists' Meeting on Tokamak Concept Innovations held 13-17 January 1986 in Vienna. Although it is the most advanced fusion reactor concept the tokamak is not without its problems. Most of these problems should be solved within the ongoing R and D studies for the next generation of tokamaks. Emphasis for this meeting was placed on innovations that would lead to substantial improvements in a tokamak reactor, even if they involved a radical departure from present thinking

  18. The physics of an ignited tokamak

    International Nuclear Information System (INIS)

    Troyon, F.

    1990-10-01

    There appears to be a consensus that time has come to embark on the design and construction of the next generation of tokamaks which is at the origin of the ITER initiative. Different proposals have been made based on different appreciation as to the size of the step which can be taken, related to considerations of cost, risk and duration of construction. A class of devices which may be considered the last the very high-field, high density ALCATOR-Frascati line of tokamaks have been proposed for some years specifically for this purpose. Today there remain three such projects: Ignitor, Ignitex and CIT. The technology chosen limits the pulse length to a few seconds. These devices have evolved through the years becoming larger and much more expensive than originally anticipated, increasing the pressure to do more than just a simple demonstration of ignition. There is another class of more ambitious devices which aim at creating long burning plasmas in conditions as close as possible to those of a tokamak reactor in order to address all the plasma physics problems associated with long burn. Three such projects, NET, the european next step after JET, ITER and JIT are good examples of this approach. The ideal would be to design a device with sufficient margin to study burning plasmas over a wide range of parameters. The object of this didactic presentation is to describe the common physics basis of all these projects, compare their expected performance using present knowledge and list the physics problems associated with a burning plasma experiment. The comparison is not meant to be a judgement since the important parameter is the cost/benefit ratio which is a matter of appreciation at this stage. 6 refs., 3 figs., 1 tab

  19. JET with a pumped divertor -- Technical issues and main results

    International Nuclear Information System (INIS)

    Bertolini, E.

    1995-01-01

    The most recent modification to JET has been the installation of a single-null pumped divertor, for active control of plasma impurities. This is to address central physics issues relevant to the design of a next step tokamak. Experiments conducted during the 1994--95 campaign, with plasma currents up to 6MA, have shown that the Mark I divertor, which makes use of strike point sweeping across the target plates, is a suitable tool to control the influx of impurities in the plasma core. The operation of a tokamak with a pumped divertor has been characterized in detail. However the divertor configuration must be optimized to better meet ITER requirements. Therefore an improved (more closed) divertor structure, which may not require sweeping, is under assembly at present (Mark II). It is designed, in addition, to allow divertor tile structures to be fully replaceable by remote handling techniques, following D-T fusion experiments. New types of events involving electromechanical interactions of plasma with the vessel and in-vessel structural components have been encountered, due to plasma vertical instabilities and disruptions (such as toroidal asymmetries of vacuum vessel forces and side-ways vessel displacements). The physics and engineering experimental work performed in JET is primarily dedicated to the finalization of the ITER design

  20. Theoretical issues in tokamak confinement: (i) Internal/edge transport barriers and (ii) runaway avalanche confinement

    International Nuclear Information System (INIS)

    Connor, J.W.; Helander, P.; Thyagaraja, A.; Andersson, F.; Fueloep, T.; Eriksson, L.-G.; Romanelli, M.

    2001-01-01

    This paper summarises a number of distinct, but related, pieces of work on key confinement issues for tokamaks, in particular the formation of internal and edge transport barriers, both within turbulent and neoclassical models, and radial diffusion of avalanching runaway electrons. First-principle simulations of tokamak turbulence and transport using the two-fluid, electromagnetic, global code CUTIE are described. The code has demonstrated the spontaneous formation of internal transport barriers near mode rational surfaces, in qualitative agreement with observations on JET and RTP. The theory of neoclassical transport in an impure, toroidal plasma has been extended to allow for steeper pressure and temperature gradients than are usually considered, and is then found to become nonlinear under conditions typical of the tokamak edge. For instance, the particle flux is found to be a nonmonotonic function of the gradients, thus allowing for a bifurcation in the ion particle flux. Finally, it is shown that radial diffusion caused by magnetic fluctuations can effectively suppress avalanches of runaway electrons if the fluctuation amplitude exceeds δB/B∼10 -3 . (author)

  1. Investigation of the influence of divertor recycling on global plasma confinement in JET ITER-like wall

    NARCIS (Netherlands)

    Tamain, P.; Joffrin, E.; Bufferand, H.; Jarvinen, A.; Brezinsek, S.; Ciraolo, G.; Delabie, E.; Frassinetti, L.; Giroud, C.; Groth, M.; Lipschultz, B.; Lomas, P.; Marsen, S.; Menmuir, S.; Oberkofler, M.; Stamp, M.; Wiesen, S.; JET-EFDA Contributors,

    2015-01-01

    Abstract The impact of the divertor geometry on global plasma confinement in type I ELMy H-mode has been investigated in the JET tokamak equipped with ITER-Like Wall. Discharges have been performed in which the position of the strike-points was changed while keeping the bulk plasma equilibrium

  2. Prospects of the Minimum Fisher Regularisation in the Experimental Analyses of Plasma Particle Transport at JET

    Czech Academy of Sciences Publication Activity Database

    Mlynář, Jan; Bonheure, G.; Murari, A.; JET EFDA, Contributors.

    2006-01-01

    Roč. 51, č. 10 (2006), s. 196 ISSN 0003-0503. [Division of Plasma Physics Meeting 2006. Philadelphia, Pennsylvania , 30.10.2006-3.11.2006] Institutional research plan: CEZ:AV0Z20430508 Keywords : Tomography * transport * neutrons * fusion * tokamak * JET Subject RIV: BL - Plasma and Gas Discharge Physics

  3. Joint research using small tokamaks

    International Nuclear Information System (INIS)

    Gryaznevich, M.P.; Bosco, E. Del; Malaquias, A.; Mank, G.; Oost, G. van; He, Yexi; Hegazy, H.; Hirose, A.; Hron, M.; Kuteev, B.; Ludwig, G.O.; Nascimento, I.C.; Silva, C.; Vorobyev, G.M.

    2005-01-01

    Small tokamaks have an important role in fusion research. More than 40 small tokamaks are operational. Research on small tokamaks has created a scientific basis for the scaling-up to larger tokamaks. Well-known scientific and engineering schools, which are now determining the main directions of fusion science and technology, have been established through research on small tokamaks. Combined efforts within a network of small and medium size tokamaks will further enhance the contribution of small tokamaks. A new concept of interactive coordinated research using small tokamaks in the mainstream fusion science areas, in testing of new diagnostics, materials and technologies as well as in education, training and broadening of the geography of fusion research in the scope of the IAEA Coordinated Research Project, is presented

  4. Tandem collimators for the JET tangential gamma-ray spectrometer

    International Nuclear Information System (INIS)

    Soare, Sorin; Balshaw, Nick; Blanchard, Patrick; Craciunescu, Teddy; Croft, David; Curuia, Marian; Edlington, Trevor; Kiptily, Vasily; Murari, Andrea; Prior, Phil; Sanders, Steven; Syme, Brian; Zoita, Vasile

    2011-01-01

    The tangential gamma-ray spectrometer (TGRS) of the JET tokamak fusion facility is an important diagnostics for investigating the fast particle evolution. A well defined field of view for the TGRS diagnostics is essential for its proper operation and this is to be determined by a rather complex system of collimators and shields both for the neutron and gamma radiations. A conceptual design for this system has been carried out with the main design target set to maximize the signal-to-background ratio at the spectrometer detector, the ratio being defined in terms of the plasma emitted gamma radiation and the gamma-ray background. As a first phase of the TGRS diagnostics upgrade a set of two tandem collimators has been designed with the aim of determining a quasi-tangential field of view through JET tokamak plasmas. A modular design of the tandem system has been developed in order to allow for the construction of different configurations for deuterium and deuterium-tritium discharges. The internal structure of the collimators consists of nuclear grade lead and high density polyethylene slabs arranged in an optimized pattern. The performance of a simplified geometry of the tandem collimator configuration has been evaluated by neutron and photon transport calculations and the numerical results show that the design parameters can be attained.

  5. Joint research using small tokamaks

    International Nuclear Information System (INIS)

    Gryaznevich, M.P.; Del Bosco, E.; Malaquias, A.; Mank, G.; Oost, G. van

    2005-01-01

    Small tokamaks have an important role in fusion research. More than 40 small tokamaks are operational. Research on small tokamaks has created a scientific basis for the scaling-up to larger tokamaks. Well-known scientific and engineering schools, which are now determining the main directions of fusion science and technology, have been established through research on small tokamaks. Combined efforts within a network of small and medium size tokamaks will further enhance the contribution of small tokamaks. A new concept of interactive co-ordinated research using small tokamaks in the mainstream fusion science areas, in testing of new diagnostics, materials and technologies as well as in education, training and broadening of the geography of fusion research in the scope of the IAEA Co-ordinated Research Project is presented. (author)

  6. Drift-kinetic Alfven modes in high performance tokamaks

    International Nuclear Information System (INIS)

    Jaun, A.; Fasoli, A.F.; Testa, D.; Vaclavik, J.; Villard, L.

    2001-01-01

    The stability of fast-particle driven Alfven eigenmodes is modeled in high performance tokamaks, successively with a conventional shear, an optimized shear and a tight aspect ratio plasma. A large bulk pressure yields global kinetic Alfven eigenmodes that are stabilized by mode conversion in the presence of a divertor. This suggests how conventional reactor scenarii could withstand significant pressure gradients from the fusion products. A large safety factor in the core q 0 >2.5 in deeply shear reversed configurations and a relatively large bulk ion Larmor radius in a low magnetic field can trigger global drift-kinetic Alfven eigenmodes that are unstable in high performance JET, NSTX and ITER plasmas. (author)

  7. Tokamaks. 2. ed.

    International Nuclear Information System (INIS)

    Wesson, John; Campbell, D.J.; Connor, J.W.

    1997-01-01

    It is interesting to recall the state of tokamak research when the first edition of this book was written. My judgement of the level of real understanding at that time is indicated by the virtual absence of comparisons of experiment with theory in that edition. The need then was for a 'handbook' which collected in a single volume the concepts and models which form the basis of everyday tokamak research. The experimental and theoretical endeavours of the subsequent decade have left almost all of this intact, but have brought a massive development of the subject. Firstly, there are now several areas where the experimental behaviour is described in terms of accepted theory. This is particularly true of currents parallel to the magnetic field, and of the stability limitations on the plasma pressure. Next there has been the research on large tokamaks, hardly started at the writing of the first edition. Now our thinking is largely based on the results from these tokamaks and this work has led to the long awaited achievement of significant amounts of fusion power. Finally, the success of tokamak research has brought us face to face with the problems involved in designing and building a tokamak reactor. The present edition maintains the aim of providing a simple introduction to basic tokamak physics, but also includes an account of the advances outlined above. (Author)

  8. An investigation of coupling of the internal kink mode to error field correction coils in tokamaks

    International Nuclear Information System (INIS)

    Lazarus, E.A.

    2013-01-01

    The coupling of the internal kink to an external m/n = 1/1 perturbation is studied for profiles that are known to result in a saturated internal kink in the limit of a cylindrical tokamak. It is found from three-dimensional equilibrium calculations that, for A ≈ 30 circular plasmas and A ≈ 3 elliptical shapes, this coupling of the boundary perturbation to the internal kink is strong; i.e., the amplitude of the m/n = 1/1 structure at q = 1 is large compared with the amplitude applied at the plasma boundary. Evidence suggests that this saturated internal kink, resulting from small field errors, is an explanation for the TEXTOR and JET measurements of q 0 remaining well below unity throughout the sawtooth cycle, as well as the distinction between sawtooth effects on the q-profile observed in TEXTOR and DIII-D. It is proposed that this excitation, which could readily be applied with error field correction coils, be explored as a mechanism for controlling sawtooth amplitudes in high-performance tokamak discharges. This result is then combined with other recent tokamak results to propose an L-mode approach to fusion in tokamaks. (paper)

  9. Internal transport barrier triggering by rational magnetic flux surfaces in tokamaks

    International Nuclear Information System (INIS)

    Joffrin, E.; Challis, C.D.; Conway, G.D.

    2003-01-01

    The formation of Internal Transport Barriers (ITBs) has been experimentally associated with the presence of rational q-surfaces in both JET and ASDEX Upgrade. The triggering mechanisms are related to the occurrence of magneto-hydrodynamic (MHD) instabilities such as mode coupling or fishbone activity. These events could locally modify the poloidal velocity and increase transiently the shearing rate to values comparable to the linear growth rate of ITG modes. For JET reversed magnetic shear scenarios, ITB emergence occurs preferentially when the minimum q reaches an integer value. In this case, transport effects localised in the vicinity of zero magnetic shear and close to rational q values may also contribute to the formation of ITBs.The role of rational q surfaces on ITB triggering stresses the importance of q profile control for advanced tokamak scenario and could contribute to lower substantially the access power to these scenarios in next step facilities. (author)

  10. Overview of recent experimental results from the DIII-D advanced tokamak program

    International Nuclear Information System (INIS)

    Burrell, K.H.

    2003-01-01

    The D III-D research program is developing the scientific basis for advanced tokamak (AT) modes of operation in order to enhance the attractiveness of the tokamak as an energy producing system. Since the last International Atomic Energy Agency (IAEA) meeting, we have made significant progress in developing the building blocks needed for AT operation: 1) We have doubled the magnetohydrodynamic (MHD) stable tokamak operating space through rotational stabilization of the resistive wall mode; 2) Using this rotational stabilization, we have achieved β N H 89 ≥ 10 for 4 τ E limited by the neoclassical tearing mode; 3) Using real-time feedback of the electron cyclotron current drive (ECCD) location, we have stabilized the (m,n) = (3,2) neoclassical tearing mode and then increased β T by 60%; 4) We have produced ECCD stabilization of the (2,1) neoclassical tearing mode in initial experiments; 5) We have made the first integrated AT demonstration discharges with current profile control using ECCD; 6) ECCD and electron cyclotron heating (ECH) have been used to control the pressure profile in high performance plasmas; and 7) We have demonstrated stationary tokamak operation for 6.5 s (36 τ E ) at the same fusion gain parameter of β N H 89 /q 95 2 ≅ 0.4 as ITER but at much higher q 95 = 4.2. We have developed general improvements applicable to conventional and advanced tokamak operating modes: 1) We have an existence proof of a mode of tokamak operation, quiescent H-mode, which has no pulsed, ELM heat load to the divertor and which can run for long periods of time (3.8 s or 25 τ E ) with constant density and constant radiated power; 2) We have demonstrated real-time disruption detection and mitigation for vertical disruption events using high pressure gas jet injection of noble gases; 3) We have found that the heat and particle fluxes to the inner strike points of balanced, double-null divertors are much smaller than to the outer strike points. (author)

  11. Implications of rf current drive theory for next step steady-state tokamak design

    International Nuclear Information System (INIS)

    Schultz, J.H.

    1985-06-01

    Two missions have been identified for a next-step tokamak experiment in the United States. The more ambitious Mission II device would be a superconducting tokamak, capable of doing long-pulse ignition demonstrations, and hopefully capable of also being able to achieve steady-state burn. A few interesting lines of approach have been identified, using a combination of logical design criteria and parametric system scans [SC85]. These include: (1) TIBER: A point-design suggested by Lawrence Livermore, that proposes a machine with the capability of demonstrating ignition, high beta (10%) and high Q (=10), using high frequency, fast-wave current drive. The TIBER topology uses moderate aspect ratio and high triangularity to achieve high beta. (2) JET Scale-up. (3) Magic5: It is argued here that an aspect ratio of 5 is a magic number for a good steady-state current drive experiment. A moderately-sized machine that achieves ignition and is capable of high Q, using either fast wave or slow wave current drive is described. (4) ET-II: The concept of a highly elongated tokamak (ET) was first proposed as a low-cost approach to Mission I, because of the possibility of achieving ohmic ignition with low-stress copper magnets. We propose that its best application is really for commercial tokamaks, using fast-wave current drive, and suggest a Mission II experiment that would be prototypical of such a reactor

  12. Simulations of Turbulence in Tokamak Edge and Effects of Self-Consistent Zonal Flows

    Science.gov (United States)

    Cohen, Bruce; Umansky, Maxim

    2013-10-01

    Progress is reported on simulations of electromagnetic drift-resistive ballooning turbulence in the tokamak edge. This extends previous work to include self-consistent zonal flows and their effects. The previous work addressed simulation of L-mode tokamak edge turbulence using the turbulence code BOUT that solves Braginskii-based plasma fluid equations in tokamak edge domain. The calculations use realistic single-null geometry and plasma parameters of the DIII-D tokamak and produce fluctuation amplitudes, fluctuation spectra, and particle and thermal fluxes that compare favorably to experimental data. In the effect of sheared ExB poloidal rotation is included with an imposed static radial electric field fitted to experimental data. In the new work here we include the radial electric field self-consistently driven by the microturbulence, which contributes to the sheared ExB poloidal rotation (zonal flow generation). We present simulations with/without zonal flows for both cylindrical geometry, as in the UCLA Large Plasma Device, and for the DIII-D tokamak L-mode cases in to quantify the influence of self-consistent zonal flows on the microturbulence and the concomitant transport. This work was performed under the auspices of the U.S. Department of Energy under contract DE-AC52-07NA27344 at the Lawrence Livermore National Laboratory.

  13. Statistical analysis of disruptions in JET

    International Nuclear Information System (INIS)

    De Vries, P.C.; Johnson, M.F.; Segui, I.

    2009-01-01

    The disruption rate (the percentage of discharges that disrupt) in JET was found to drop steadily over the years. Recent campaigns (2005-2007) show a yearly averaged disruption rate of only 6% while from 1991 to 1995 this was often higher than 20%. Besides the disruption rate, the so-called disruptivity, or the likelihood of a disruption depending on the plasma parameters, has been determined. The disruptivity of plasmas was found to be significantly higher close to the three main operational boundaries for tokamaks; the low-q, high density and β-limit. The frequency at which JET operated close to the density-limit increased six fold over the last decade; however, only a small reduction in disruptivity was found. Similarly the disruptivity close to the low-q and β-limit was found to be unchanged. The most significant reduction in disruptivity was found far from the operational boundaries, leading to the conclusion that the improved disruption rate is due to a better technical capability of operating JET, instead of safer operations close to the physics limits. The statistics showed that a simple protection system was able to mitigate the forces of a large fraction of disruptions, although it has proved to be at present more difficult to ameliorate the heat flux.

  14. Simulations of Tokamak Edge Turbulence Including Self-Consistent Zonal Flows

    Science.gov (United States)

    Cohen, Bruce; Umansky, Maxim

    2013-10-01

    Progress on simulations of electromagnetic drift-resistive ballooning turbulence in the tokamak edge is summarized in this mini-conference talk. A more detailed report on this work is presented in a poster at this conference. This work extends our previous work to include self-consistent zonal flows and their effects. The previous work addressed the simulation of L-mode tokamak edge turbulence using the turbulence code BOUT. The calculations used realistic single-null geometry and plasma parameters of the DIII-D tokamak and produced fluctuation amplitudes, fluctuation spectra, and particle and thermal fluxes that compare favorably to experimental data. In the effect of sheared ExB poloidal rotation is included with an imposed static radial electric field fitted to experimental data. In the new work here we include the radial electric field self-consistently driven by the microturbulence, which contributes to the sheared ExB poloidal rotation (zonal flow generation). We present simulations with/without zonal flows for both cylindrical geometry, as in the UCLA Large Plasma Device, and for the DIII-D tokamak L-mode cases in to quantify the influence of self-consistent zonal flows on the microturbulence and the concomitant transport. This work was performed under the auspices of the US Department of Energy under contract DE-AC52-07NA27344 at the Lawrence Livermore National Laboratory.

  15. Comparison of different current transducers used at JET within the range 5–100 kA for plasma control and monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Salmon, R., E-mail: robjsalmon@gmail.com; Smith, P.; West, A.; Shaw, S.R.; Rendell, D.

    2015-10-15

    Highlights: • Zero-flux current transducers with sensory windings, Hall-effect DCCTs, Rogowski coils, shunt resistors and Faraday effect current transducers are reviewed. • All technologies have displayed good performance over 30 years of operation. • Faraday-effect current transducers have improved accuracy of the toroidal magnets current measurement on JET to 0.1%. • The improvement in accuracy has improved resolution on JET plasma kinetic profiles. - Abstract: The JET machine uses a variety of current transducers for control and protection of the plasma, the coils and their associated power supplies. This paper reviews the various measuring technologies, within the range 5–100 kA, used on JET to assist with the selection of high-current transducers for future plasma control/tokamak applications; these include Rogowski coils, coaxial shunts, Hall-effect transducers, zero-flux CTs and a Faraday-effect optical transducer. The paper considers reliability, accuracy and usability based on up to 30 years of operational experience of the transducers. Accuracy of the magnet current measurements is important in the control of tokamak plasmas and there has been considerable effort to improve it. Recently a Faraday-effect optical current sensor has been used to measure up to 67 kA in the Toroidal Field (TF) coil circuit. This measurement system has been calibrated at JET to verify its 0.1% accuracy. In addition, the data acquisition system for this measurement is automatically calibrated at the start of each JET pulse. The improved accuracy has been shown to enhance the spatial consistency of kinetic profiles at JET [1]. Due to its portability the JET project intends to employ the same Faraday-effect current transducer to calibrate other high current transducers by temporarily fitting it to other busbars, such as those in the Ohmic Heating network.

  16. Gas jet disruption mitigation studies on Alcator C-Mod

    International Nuclear Information System (INIS)

    Granetz, R.; Whyte, D.G.; Izzo, V.A.; Biewer, T.; Reinke, M.L.; Terry, J.; Bader, A.; Bakhtiari, M.; Jernigan, T.; Wurden, G.

    2006-01-01

    Damaging effects of disruptions are a major concern for Alcator C-Mod, ITER and future tokamak reactors. High-pressure noble gas jet injection is a mitigation technique which potentially satisfies the operational requirements of fast response time and reliability, while still being benign to subsequent discharges. Disruption mitigation experiments using an optimized gas jet injection system are being carried out on Alcator C-Mod to study the physics of gas jet penetration into high pressure plasmas, as well as the ability of the gas jet impurities to convert plasma energy into radiation on timescales consistent with C-Mod's fast quench times, and to reduce halo currents given C-Mod's high-current density. The dependence of impurity penetration and effectiveness on noble gas species (He, Ne, Ar, Kr) is also being studied. It is found that the high-pressure neutral gas jet does not penetrate deeply into the C-Mod plasma, and yet prompt core thermal quenches are observed on all gas jet shots. 3D MHD modelling of the disruption physics with NIMROD shows that edge cooling of the plasma triggers fast growing tearing modes which rapidly produce a stochastic region in the core of the plasma and loss of thermal energy. This may explain the apparent effectiveness of the gas jet in C-Mod despite its limited penetration. The higher-Z gases (Ne, Ar, Kr) also proved effective at reducing halo currents and decreasing thermal deposition to the divertor surfaces. In addition, noble gas jet injection proved to be benign for plasma operation with C-Mod's metal (Mo) wall, actually improving the reliability of the startup in the following discharge

  17. Laser driven pellet refuelling for JET (and reactor) uses

    International Nuclear Information System (INIS)

    Spalding, I.J.

    1978-11-01

    Published estimates of pellet sizes and velocities required to refuel JET and post-JET experiments are summarized. Possible advantages and difficulties of accelerating solid, unconstrained hydrogenic (and also jacketed) pellets to these velocities using laser techniques are then discussed. An essential problem to be solved is adequate axial guidance of the pellet during its acceleration, since laser pulse durations of many sound-transit times (in the solid D 2 ) are necessary to avoid shock-heating the pellet. It is shown that Culham's multikilojoule CO 2 TROJAN laser facility is well suited to testing many of the concepts proposed. In particular it is shown that successful verification, and subsequent optimization, of such (novel) techniques would permit single shot tests of contemporary pellet ablation theories by the injection of approximately 1 mm diameter D 2 pellets at velocities 6 cm s -1 into the JET plasma. Means for scaling these techniques to repetition rates of order 10 Hz, and to the 1 cm pellet diameters possibly required in a working Tokamak reactor, are also discussed. (author)

  18. Spectra of germanium and selenium in the 50-350 A region from the PLT tokamak plasma

    International Nuclear Information System (INIS)

    Stratton, B.C.; Hodge, W.L.; Moos, H.W.; Schwob, J.L.; Suckewer, S.; Finkenthal, M.; Cohen, S.

    1983-03-01

    Spectra of germanium and selenium injected into the PLT tokamak plasma were observed in the 50 to 350 A region for GeXIV-XXV (KI to OI-like) and SeXVI-XXIV (KI to NaI-like). A number of 3p/sup k/-3p/sup k-1/3d transitions predicted by isoelectronic sequence extrapolation have been identified. Also, previously identified lines from ions in the AlI to OI-like and KI-like isoelectronic sequences have been observed in the tokamak plasma

  19. Gas jet disruption mitigation studies on Alcator C-Mod and DIII-D

    International Nuclear Information System (INIS)

    Granetz, R.S.; Hollmann, E.M.; Whyte, D.G.; Izzo, V.A.; Antar, G.Y.; Bader, A.; Bakhtiari, M.; Biewer, T.; Boedo, J.A.; Evans, T.E.; Hutchinson, I.H.; Jernigan, T.C.; Gray, D.S.; Groth, M.; Humphreys, D.A.; Lasnier, C.J.; Moyer, R.A.; Parks, P.B.; Reinke, M.L.; Rudakov, D.L.; Strait, E.J.; Terry, J.L.; Wesley, J.; West, W.P.; Wurden, G.; Yu, J.

    2007-01-01

    High-pressure noble gas jet injection is a mitigation technique which potentially satisfies the requirements of fast response time and reliability, without degrading subsequent discharges. Previously reported gas jet experiments on DIII-D showed good success at reducing deleterious disruption effects. In this paper, results of recent gas jet disruption mitigation experiments on Alcator C-Mod and DIII-D are reported. Jointly, these experiments have greatly improved the understanding of gas jet dynamics and the processes involved in mitigating disruption effects. In both machines, the sequence of events following gas injection is observed to be quite similar: the jet neutrals stop near the plasma edge, the edge temperature collapses and large MHD modes are quickly destabilized, mixing the hot plasma core with the edge impurity ions and radiating away the plasma thermal energy. High radiated power fractions are achieved, thus reducing the conducted heat loads to the chamber walls and divertor. A significant (2 x or more) reduction in halo current is also observed. Runaway electron generation is small or absent. These similar results in two quite different tokamaks are encouraging for the applicability of this disruption mitigation technique to ITER

  20. Internal transport barrier triggering by rational magnetic flux surfaces in tokamaks

    International Nuclear Information System (INIS)

    Joffrin, E.; Challis, C.D.; Conway, G.D.

    2003-01-01

    The formation of internal transport barriers (ITBs) has been experimentally associated with the presence of rational q surfaces in both JET and ASDEX Upgrade. The triggering mechanisms are related to the occurrence of magneto-hydrodynamic (MHD) instabilities such as mode coupling and fishbone activity. These events could locally modify the poloidal velocity and increase transiently the shearing rate to values comparable with the linear growth rate of ion temperature gradient modes. For JET reversed magnetic shear scenarios, ITB emergence occurs preferentially when the minimum q reaches an integral value. In this case, transport effects localized in the vicinity of zero magnetic shear and close to rational q values may be at the origin of ITB formation. The role of rational q surfaces in ITB triggering stresses the importance of q profile control for an advanced tokamak scenario and could assist in substantially lowering the access power to these scenarios in next step facilities. (author)

  1. Status of the tokamak program

    Science.gov (United States)

    Sheffield, J.

    1981-08-01

    For a specific configuration of magnetic field and plasma to be economically attractive as a commercial source of energy, it must contain a high-pressure plasma in a stable fashion while thermally isolating the plasma from the walls of the containment vessel. The tokamak magnetic configuration is presently the most successful in terms of reaching the considered goals. Tokamaks were developed in the USSR in a program initiated in the mid-1950s. By the early 1970s tokamaks were operating not only in the USSR but also in the U.S., Australia, Europe, and Japan. The advanced state of the tokamak program is indicated by the fact that it is used as a testbed for generic fusion development - for auxiliary heating, diagnostics, materials - as well as for specific tokamak advancement. This has occurred because it is the most economic source of a large, reproducible, hot, dense plasma. The basic tokamak is considered along with tokamak improvements, impurity control, additional heating, particle and power balance in a tokamak, aspects of microscopic transport, and macroscopic stability.

  2. Assessment of the effect of parallel temperature gradients in the JET SOL on Te measured by divertor target Langmuir probes

    NARCIS (Netherlands)

    Ďuran, I.; Ješko, K.; Fuchs, V.; Groth, M.; Guillemaut, C.; Gunn, J.P.; Horáček, J.; Pitts, R.A.; Tskhakaya, D.

    2015-01-01

    Abstract Higher than expected electron temperatures (Te) are often measured by divertor Langmuir probes (LP) in high recycling and detached regimes in JET and other tokamaks. As a possible mechanism to explain this discrepancy, we investigate the effect of penetration of fast, almost collisionless

  3. Impurity production and transport in the boundary layer of tokamaks

    International Nuclear Information System (INIS)

    McCracken, G.M.

    1987-01-01

    The processes by which impurities are produced and enter the discharge are discussed. Emphasis is placed on sputtering at the limiter and an analytical global model is described which incorporates the self-stabilizing effects whch control the edge temperature. Predictions of the scaling of edge temperature and of total radiated power are compared with experimental data from JET and other tokamaks operating with limiters. Under many conditions the scaling of the edge conditions and of the radiated power is accurately predicted. Impurity transport in the boundary and the question of how to control the boundary layer is then discussed. The example of the Impurity Control Limiter on DITE is described. (author)

  4. The scientific success of JET

    International Nuclear Information System (INIS)

    Keilhacker, M.; Gibson, A.; Gormezano, C.; Rebut, P.H.

    2001-01-01

    The paper highlights the JET work in physics and technology during the period of the JET Joint Undertaking (1978-1999), with special emphasis on what has been learned for extrapolation to a NEXT STEP device. - Global confinement scaling has been extended to high currents and heating powers. Dimensionless scaling experiments of ELMy H mode plasmas suggest that bulk plasma transport is gyro-Bohm and predict ignition for a device with ITER-FDR parameters. Experiments in which the plasma elongation and triangularity were varied independently show a strong increase of confinement time with elongation (τ E ∼κ α 0.8±0.3 ), thus supporting a basic design principle of ITER-FEAT. With the Pellet Enhanced Performance (PEP) mode, JET has discovered the beneficial effect of reversed magnetic shear on confinement, opening the possibility of advanced tokamak scenarios. - With a three stage programme of progressively more closed divertors, JET has demonstrated the benefits of divertor closure, in particular, of high divertor neutral pressure which facilitates helium removal. It has also shown that in detached (or semidetached) radiative divertor plasmas the average power load on the target plates of a NEXT STEP device should be tolerable but, in addition, that the transient power loads during ELMs could cause problems. - In 1991 JET has demonstrated the first ever controlled production of a megawatt of fusion power. More extensive D-T experiments in 1997 (DTE1) have established new records in fusion performance: 16 MW transient fusion power with Q in =0.62 (i.e. close to breakeven, Q in =1) and 4 MW steady state fusion power with Q in =0.18 for 4 s. DTE1 has also allowed a successful test of various reactor ICRF heating schemes and a clear demonstration of alpha particle heating, consistent with classical expectations. - JET has developed and tested some of the most important technologies for a NEXT STEP and a reactor, in particular the safe handling of tritium and the

  5. A two-time-scale dynamic-model approach for magnetic and kinetic profile control in advanced tokamak scenarios on JET

    International Nuclear Information System (INIS)

    Moreau, D.; Mazon, D.; Ariola, M.; Tommasi, G. De; Laborde, L.; Piccolo, F.; Sartori, F.; Zabeo, L.; Boboc, A.; Brix, M.; Challis, C.D.; Felton, R.; Hawkes, N.; Tala, T.; Bouvier, E.; Cordoliani, V.; Brzozowski, J.; Cocilovo, V.; Crisanti, F.; Luna, E. de la

    2008-01-01

    Real-time simultaneous control of several radially distributed magnetic and kinetic plasma parameters is being investigated on JET, in view of developing integrated control of advanced tokamak scenarios. This paper describes the new model-based profile controller which has been implemented during the 2006-2007 experimental campaigns. The controller aims to use the combination of heating and current drive (H and CD) systems-and optionally the poloidal field (PF) system-in an optimal way to regulate the evolution of plasma parameter profiles such as the safety factor, q(x), and gyro-normalized temperature gradient, ρ Te *(x). In the first part of the paper, a technique for the experimental identification of a minimal dynamic plasma model is described, taking into account the physical structure and couplings of the transport equations, but making no quantitative assumptions on the transport coefficients or on their dependences. To cope with the high dimensionality of the state space and the large ratio between the time scales involved, the model identification procedure and the controller design both make use of the theory of singularly perturbed systems by means of a two-time-scale approximation. The second part of the paper provides the theoretical basis for the controller design. The profile controller is articulated around two composite feedback loops operating on the magnetic and kinetic time scales, respectively, and supplemented by a feedforward compensation of density variations. For any chosen set of target profiles, the closest self-consistent state achievable with the available actuators is uniquely defined. It is reached, with no steady state offset, through a near-optimal proportional-integral control algorithm. Conventional optimal control is recovered in the limiting case where the ratio of the plasma confinement time to the resistive diffusion time tends to zero. Closed-loop simulations of the controller response have been performed in preparation for

  6. Hot spots on the neutralizer plates of a tokamak

    International Nuclear Information System (INIS)

    Krasheninnikov, S.I.

    1991-01-01

    The formation of hot spots on the neutralizing surfaces of tokamaks may be one of the reasons for the entry of large impurity fluxes into the plasmas of TFTR and JET (the so-called carbon catastrophe or carbon bloom) with high auxiliary heating powers. At this time it is unclear whether these hot spots are caused just by nonuniformities on the neutralizer surface or whether their appearance is the result of some more general behavior, with the surface nonuniformities only showing up as seed perturbations. In this paper it is shown that hot spots can also develop on smooth surfaces of carbon neutralizer plates as a result of the contraction of a heat flux incident on the plates

  7. Present status of Tokamak research

    International Nuclear Information System (INIS)

    Basu, Jayanta

    1991-01-01

    The scenario of thermonuclear fusion research is presented, and the tokamak which is the most promising candidate as a fusion reactor is introduced. A brief survey is given of the most noteworthy tokamaks in the global context, and fusion programmes relating to Next Step devices are outlined. Supplementary heating of tokamak plasma by different methods is briefly reviewed; the latest achievements in heating to fusion temperatures are also reported. The progress towards the high value of the fusion product necessary for ignition is described. The improvement in plasma confinement brought about especially by the H-mode, is discussed. The latest situation in pushing up Β for increasing the efficiency of a tokamak is elucidated. Mention is made of the different types of wall treatment of the tokamak vessel for impurity control, which has led to a significant improvement in tokamak performance. Different methods of current drive for steady state tokamak operation are reviewed, and the issue of current drive efficiency is addressed. A short resume is given of the various diagnostic methods which are employed on a routine basis in the major tokamak centres. A few diagnostics recently developed or proposed in the context of the advanced tokamaks as well as the Next Step devices are indicated. The important role of the interplay between theory, experiment and simulation is noted, and the areas of investigation requiring concerted effort for further progress in tokamak research are identified. (author). 17 refs

  8. Comparison of Theory with Rotation Measurements in JET ICRH Plasmas

    International Nuclear Information System (INIS)

    R.V. Budny; C.S. Chang; C. Giroud; R.J. Goldston; D. McCune; J. Ongena; F.W. Perkins; R.B. White; K.-D. Zastrow; and contributors to the EFDA-JET work programme

    2001-01-01

    Plasma rotation appears to improve plasma performance by increasing the E x B flow shearing rate, thus decreasing radial correlations in the microturbulence. Also, plasma rotation can increase the stability to resistive MHD modes. In the Joint European Torus (JET), toroidal rotation rates omega (subscript ''tor'') with high Mach numbers are generally measured in NBI-heated plasmas (since the neutral beams aim in the co-plasma current direction). They are considerably lower with only ICRH (and Ohmic) heating, but still surprisingly large considering that ICRH appears to inject relatively small amounts of angular momentum. Either the applied torques are larger than naively expected, or the anomalous transport of angular momentum is smaller than expected. Since ICRH is one of the main candidates for heating next-step tokamaks, and for creating burning plasmas in future tokamak reactors, this paper attempts to understand ICRH-induced plasma rotation

  9. Neutral-beam requirements for compression-boosted ignited tokamak plasmas

    International Nuclear Information System (INIS)

    Cohn, D.R.; Jassby, D.L.; Kreischer, K.

    1977-12-01

    Neutral-beam energies of 200 to 500-keV D 0 may be required to insure adequate penetration into the center of ignition-sized tokamak plasmas. However, the beam energy requirement can be reduced by using a start-up scenario in which the final plasma is formed by major-radius compression of a beam-heated plasma whose density-radius product, na, is determined by satisfactory neutral-beam penetration. ''Compression boosting'' is attractive only for plasmas in which ntau/sub E/ increases with na, because a major-radius compression C increases na by C 3 / 2 . The dependence on C of beam energy and beam power for plasmas which obey ''empirical scaling laws'' of the type ntau/sub E/ varies as (na) 2 is analyzed. The dependences on C of stored magnetic energy and TF-coil power dissipation are also determined. It is found that a compression ratio of 1.5 to attain the ignited plasma permits adequate penetration by 150-keV D 0 beams

  10. Status of the COMPASS tokamak and characterization of the first H-mode

    Science.gov (United States)

    Pánek, R.; Adámek, J.; Aftanas, M.; Bílková, P.; Böhm, P.; Brochard, F.; Cahyna, P.; Cavalier, J.; Dejarnac, R.; Dimitrova, M.; Grover, O.; Harrison, J.; Háček, P.; Havlíček, J.; Havránek, A.; Horáček, J.; Hron, M.; Imríšek, M.; Janky, F.; Kirk, A.; Komm, M.; Kovařík, K.; Krbec, J.; Kripner, L.; Markovič, T.; Mitošinková, K.; Mlynář, J.; Naydenkova, D.; Peterka, M.; Seidl, J.; Stöckel, J.; Štefániková, E.; Tomeš, M.; Urban, J.; Vondráček, P.; Varavin, M.; Varju, J.; Weinzettl, V.; Zajac, J.; the COMPASS Team

    2016-01-01

    This paper summarizes the status of the COMPASS tokamak, its comprehensive diagnostic equipment and plasma scenarios as a baseline for the future studies. The former COMPASS-D tokamak was in operation at UKAEA Culham, UK in 1992-2002. Later, the device was transferred to the Institute of Plasma Physics of the Academy of Sciences of the Czech Republic (IPP AS CR), where it was installed during 2006-2011. Since 2012 the device has been in a full operation with Type-I and Type-III ELMy H-modes as a base scenario. This enables together with the ITER-like plasma shape and flexible NBI heating system (two injectors enabling co- or balanced injection) to perform ITER relevant studies in different parameter range to the other tokamaks (ASDEX-Upgrade, DIII-D, JET) and to contribute to the ITER scallings. In addition to the description of the device, current status and the main diagnostic equipment, the paper focuses on the characterization of the Ohmic as well as NBI-assisted H-modes. Moreover, Edge Localized Modes (ELMs) are categorized based on their frequency dependence on power density flowing across separatrix. The filamentary structure of ELMs is studied and the parallel heat flux in individual filaments is measured by probes on the outer mid-plane and in the divertor. The measurements are supported by observation of ELM and inter-ELM filaments by an ultra-fast camera.

  11. Tokamak engineering mechanics

    CERN Document Server

    Song, Yuntao; Du, Shijun

    2013-01-01

    Tokamak Engineering Mechanics offers concise and thorough coverage of engineering mechanics theory and application for tokamaks, and the material is reinforced by numerous examples. Chapter topics include general principles, static mechanics, dynamic mechanics, thermal fluid mechanics and multiphysics structural mechanics of tokamak structure analysis. The theoretical principle of the design and the methods of the analysis for various components and load conditions are presented, while the latest engineering technologies are also introduced. The book will provide readers involved in the study

  12. The technological achievements and experience at JET

    International Nuclear Information System (INIS)

    Pick, M.

    1998-12-01

    The Joint European Torus, JET, the largest and most successful Tokamak in the world, was conceived from the start as a research project with very ambitious aims and a bold approach to extrapolations of the physics and technology base as well as the international nature of its organisation. Throughout its operating life JET has maintained this approach and, with its innovative and flexible design, has extended its performance far beyond the initially intended boundaries thereby retaining a lead in virtually all areas of fusion research. JET has shown a willingness to venture far beyond the technology base of the time into new areas and dimensions. The paper will highlight a few examples which illustrate the approach taken in JET to work closely with industry and the European Associations to extend the technology beyond the current state of the art whilst maintaining a tight grip on the fundamental requirements of cost and time schedule. These range from large scale integrated systems as well as small scale technological breakthroughs. Large scale systems include the Active Gas Handling System for the on-line reprocessing of the tritium-deuterium fuel, the Remote Handling System which was integrated into the JET machine from the very beginning, the JET Power Supply system as well as, most importantly, the design of the JET structure itself which permitted the fast maintenance and repair of all major sub-units. Other notable advances include the Neutral Beam Injection and Radio Frequency Heating systems, the large open structure cryo-pumps and the novel cryo-transmission lines. Some of the associated technologies required major advances in the area of diagnostics, high power handling components, carbon fibre reinforced carbon materials as well as in the whole field of beryllium technology and beryllium handling. The success of JET has shown that it serves as a model for future machines both from an engineering point of view as well as in its approach to management

  13. Status of tokamak research

    International Nuclear Information System (INIS)

    Rawls, J.M.

    1979-10-01

    An overall review of the tokamak program is given with particular emphasis upon developments over the past five years in the theoretical and experimental elements of the program. A summary of the key operating parameters for the principal tokamaks throughout the world is given. Also discussed are key issues in plasma confinement, plasma heating, and tokamak design

  14. Q-profiles in JET

    International Nuclear Information System (INIS)

    Gill, R.D.; Edwards, A.W.; Keegan, B.; Lazzaro, E.; O'Rourke, J.; Weller, A.; Zasche, D.

    1989-01-01

    Tokamak q-profiles play a central role in the determination of plasma stability and q(r) towards the plasma centre is particularly important for the sawtooth instability. On JET, q(r) has been determined from magnetic measurements and Faraday rotation. Further information about the position of the q=1 surface has been found from the sawtooth inversion radius, the position of the snake and the resonance effect observed on visible light and X-ray emission during pellet injection. In addition the shear at the q=1 surface has been measured from pellet ablation. This result is supported by the movement of the snake caused by a sawtooth crash. A summary of these data will be made after presenting the new results from pellet ablation. (author) 5 refs., 8 figs

  15. Tokamak ARC damage

    International Nuclear Information System (INIS)

    Murray, J.G.; Gorker, G.E.

    1985-01-01

    Tokamak fusion reactors will have large plasma currents of approximately 10 MA with hundreds of megajoules stored in the magnetic fields. When a major plasma instability occurs, the disruption of the plasma current induces voltage in the adjacent conducting structures, giving rise to large transient currents. The induced voltages may be sufficiently high to cause arcing across sector gaps or from one protruding component to another. This report reviews a tokamak arcing scenario and provides guidelines for designing tokamaks to minimize the possibility of arc damage

  16. Tokamak ARC damage

    Energy Technology Data Exchange (ETDEWEB)

    Murray, J.G.; Gorker, G.E.

    1985-01-01

    Tokamak fusion reactors will have large plasma currents of approximately 10 MA with hundreds of megajoules stored in the magnetic fields. When a major plasma instability occurs, the disruption of the plasma current induces voltage in the adjacent conducting structures, giving rise to large transient currents. The induced voltages may be sufficiently high to cause arcing across sector gaps or from one protruding component to another. This report reviews a tokamak arcing scenario and provides guidelines for designing tokamaks to minimize the possibility of arc damage.

  17. The technological achievements and experience at JET

    International Nuclear Information System (INIS)

    Pick, M.A.

    1999-01-01

    The Joint European Torus, JET, the largest and most successful Tokamak in the world, was conceived from the start as a research project with very ambitious aims and a bold approach to extrapolations of the physics and technology base as well as the international nature of its organisation. Throughout its operating life the JET team has maintained this approach and, with its innovative and flexible design, has extended its performance far beyond the initially intended boundaries thereby retaining a lead in virtually all areas of fusion research. The team has shown a willingness to venture far beyond the technology base of the time into new areas and dimensions. The paper will highlight a few examples which illustrate the approach taken in JET to work closely with industry and the European Associations to extend the technology beyond the current state of the art whilst maintaining a tight grip on the fundamental requirements of cost and time schedule. These range from large scale integrated systems as well as small scale technological breakthroughs. Large scale systems include the Active Gas Handling System for the on-line reprocessing of the tritium-deuterium fuel, the Remote Handling System which was integrated into the JET machine from the very beginning, the JET Power Supply system as well as, most importantly, the design of the JET structure itself which permitted the fast maintenance and repair of all major sub-units. Other notable advances include the Neutral Beam Injection and Radio Frequency Heating systems, the large open structure cryo-pumps and the novel cryo-transmission lines. Some of the associated technologies required major advances in the area of diagnostics, high power handling components, carbon fibre reinforced carbon materials as well as in the whole field of beryllium technology and beryllium handling. (orig.)

  18. Experimental investigation of edge localised modes in JET

    International Nuclear Information System (INIS)

    Lindholm Colton, A.

    1993-08-01

    Edge Localised Modes (ELMs) in the JET tokamak have been studied experimentally, using density profile and fluctuation data from a multichannel reflectometer and temperature profile data from an ECE heterodyne radiometer. The following topics have been investigated: The radial extent and localisation of the density and temperature profile perturbations caused by the ELMs. Fluctuations in the density and magnetic field in connection with the ELMs. The correlation between the repetition frequency of the L-H transition ELMs, and the plasma edge temperature and density. Trajectories in n-T space prior to ELMs later in the H-mode. (au) (39 refs.)

  19. Tokamak reactor studies

    International Nuclear Information System (INIS)

    Baker, C.C.

    1981-01-01

    This paper presents an overview of tokamak reactor studies with particular attention to commercial reactor concepts developed within the last three years. Emphasis is placed on DT fueled reactors for electricity production. A brief history of tokamak reactor studies is presented. The STARFIRE, NUWMAK, and HFCTR studies are highlighted. Recent developments that have increased the commercial attractiveness of tokamak reactor designs are discussed. These developments include smaller plant sizes, higher first wall loadings, improved maintenance concepts, steady-state operation, non-divertor particle control, and improved reactor safety features

  20. Disassembly of JT-60 tokamak device and ancillary facilities for JT-60 tokamak

    International Nuclear Information System (INIS)

    Okano, Fuminori; Ichige, Hisashi; Miyo, Yasuhiko; Kaminaga, Atsushi; Sasajima, Tadayuki; Nishiyama, Tomokazu; Yagyu, Jun-ichi; Ishige, Youichi; Suzuki, Hiroaki; Komuro, Kenichi; Sakasai, Akira; Ikeda, Yoshitaka

    2014-03-01

    The disassembly of JT-60 tokamak device and its peripheral equipments, where the total weight was about 5400 tons, started in 2009 and accomplished in October 2012. This disassembly was required process for JT-60SA project, which is the Satellite Tokamak project under Japan-EU international corroboration to modify the JT-60 to the superconducting tokamak. This work was the first experience of disassembling a large radioactive fusion device based on Radiation Hazard Prevention Act in Japan. The cutting was one of the main problems in this disassembly, such as to cut the welded parts together with toroidal field coils, and to cut the vacuum vessel into two. After solving these problems, the disassembly completed without disaster and accident. This report presents the outline of the JT-60 disassembly, especially tokamak device and ancillary facilities for tokamak device. (author)

  1. Plasma edge physics in an actively cooled tokamak

    International Nuclear Information System (INIS)

    Gunn, J.P.; Adamek, A.; Boucher, C.

    2005-01-01

    Tore Supra is a large tokamak with a plasma of circular cross section (major radius 2.4 m and minor radius 0.72 m) lying on a toroidal limiter. Tore Supra's main mission is the development of technology to inject up to 25 MW of microwave heating power and extract it continuously for up to 1000 s in steady state without uncontrolled overheating of, or outgassing from, plasma-facing components. The entire first wall of the tokamak is actively cooled by a high pressure water loop and special carbon fiber composite materials have been designed to handle power fluxes up to 10 MW/m 2 . The edge plasma on open magnetic flux surfaces that intersect solid objects plays an important role in the overall behaviour of the plasma. The transport of sputtered impurity ions and the fueling of the core plasma are largely governed by edge plasma density, temperature, and flow profiles. Measurements of these quantities are becoming more reliable and frequent in many tokamaks, and it has become clear that we do not understand them very well. Classical two-dimensional fluid modelling fails to reproduce many aspects of the experimental observations such as the significant thickness of the edge plasma, and the near-sonic flows that occur where none should be expected. It is suspected that plasma turbulence is responsible for these anomalies. In the Tore Supra tokamak, various kinds of Langmuir probes are used to characterize the edge plasma. We will present original measurements that demonstrate the universality of many phenomena that have been observed in X-point divertor tokamaks, especially concerning the ion flows. As in the JET tokamak, surprisingly large values of parallel Mach number are measured midway between the two strike zones, where one would expect to find nearly stagnant plasma if the particle source were poloidally uniform. We will present results of a novel experiment that provides evidence for a poloidally localized particle and energy source on the outboard midplane of

  2. Vessel thermal map real-time system for the JET tokamak

    Directory of Open Access Journals (Sweden)

    D. Alves

    2012-05-01

    Full Text Available The installation of international thermonuclear experimental reactor-relevant materials for the plasma facing components (PFCs in the Joint European Torus (JET is expected to have a strong impact on the operation and protection of the experiment. In particular, the use of all-beryllium tiles, which deteriorate at a substantially lower temperature than the formerly installed carbon fiber composite tiles, imposes strict thermal restrictions on the PFCs during operation. Prompt and precise responses are therefore required whenever anomalous temperatures are detected. The new vessel thermal map real-time application collects the temperature measurements provided by dedicated pyrometers and infrared cameras, groups them according to spatial location and probable offending heat source, and raises alarms that will trigger appropriate protective responses. In the context of the JET global scheme for the protection of the new wall, the system is required to run on a 10 ms cycle communicating with other systems through the real-time data network. In order to meet these requirements a commercial off-the-shelf solution has been adopted based on standard x86 multicore technology. Linux and the multithreaded application real-time executor (MARTe software framework were respectively the operating system of choice and the real-time framework used to build the application. This paper presents an overview of the system with particular technical focus on the configuration of its real-time capability and the benefits of the modular development approach and advanced tools provided by the MARTe framework.

  3. Real-time determination of confinement parameters in JET

    International Nuclear Information System (INIS)

    Barana, Oliviero; Joffrin, E.; Murari, A.; Sartori, F.

    2003-01-01

    The main confinement parameters, like the internal inductance l i and the diamagnetic poloidal beta β DIA , are of particular relevance for a reliable real-time control system of next step tokamaks. These quantities have been obtained at Joint European Torus (JET), with a precision more than satisfactory for real-time applications, through a method, known as BETALI, that uses the Shafranov integrals S 1 , S 2 and S 3 . Since S 1 , S 2 and S 3 are defined on the plasma boundary, a technique, that exploits the real-time boundary code XLOC, has been expressively developed to determine the last closed flux surface (LCFS). BETALI has been verified on several experimental plasma configurations, giving very encouraging results both in the limiter and x-point phase of the discharges. The compatibility with the time restrictions has also been tested successfully. This application has, therefore, been implemented and it has already been used during last JET campaigns

  4. Tokamak confinement scaling laws

    International Nuclear Information System (INIS)

    Connor, J.

    1998-01-01

    The scaling of energy confinement with engineering parameters, such as plasma current and major radius, is important for establishing the size of an ignited fusion device. Tokamaks exhibit a variety of modes of operation with different confinement properties. At present there is no adequate first principles theory to predict tokamak energy confinement and the empirical scaling method is the preferred approach to designing next step tokamaks. This paper reviews a number of robust theoretical concepts, such as dimensional analysis and stability boundaries, which provide a framework for characterising and understanding tokamak confinement and, therefore, generate more confidence in using empirical laws for extrapolation to future devices. (author)

  5. Results from deuterium-tritium tokamak confinement experiments

    International Nuclear Information System (INIS)

    Hawryluk, R.J.

    1997-02-01

    Recent scientific and technical progress in magnetic fusion experiments has resulted in the achievement of plasma parameters (density and temperature) which enabled the production of significant bursts of fusion power from deuterium-tritium fuels and the first studies of the physics of burning plasmas. The key scientific issues in the reacting plasma core are plasma confinement, magnetohydrodynamic (MHD) stability, and the confinement and loss of energetic fusion products from the reacting fuel ions. Progress in the development of regimes of operation which have both good confinement and are MHD stable have enabled a broad study of burning plasma physics issues. A review of the technical and scientific results from the deuterium-tritium experiments on the Joint European Torus (JET) and the Tokamak Fusion Test Reactor (TFTR) is given with particular emphasis on alpha-particle physics issues

  6. Carbon deposition and hydrogen retention in tokamak

    International Nuclear Information System (INIS)

    Tanabe, Tetsuo

    2006-01-01

    The results of measurements on co-deposition of hydrogen isotopes and wall materials, hydrogen retention, redeposition of carbon and deposition of hydrogen on PMI of JT-60U are described. From above results, selection of plasma facing material and ability of carbon wall is discussed. Selection of plasma facing materials in fusion reactor, characteristics of carbon materials as the plasma facing materials, erosion, transport and deposition of carbon impurity, deposition of tritium in JET, results of PMI in JT-60, application of carbon materials to PFM of ITER, and future problems are stated. Tritium co-deposition in ITER, erosion and transport of carbon in tokamak, distribution of tritium deposition on graphite tile used as bumper limiter of TFTR, and measurement results of deposition of tritium on the Mark-IIA divertor tile and comparison between them are described. (S.Y.)

  7. Improvement of the bandwidth of the transient digitizers in the LIDAR Thomson scattering diagnostic on JET

    International Nuclear Information System (INIS)

    Kristensen, E.

    1990-06-01

    The main limitation on the spatial resolution of the LIDAR Thomson scattering diagnostic on the JET tokamak is due to the narrow bandwidth of the detection system. The transient digitizers, Tektronik 7912AD, are the main contributors to the narrow bandwidth. It is shown how the digitizers can be modified to improve the response time from approx. 480 to 410 ps. (author)

  8. Zeff from spectroscopic bremsstrahlung measurements at ASDEX Upgrade and JET

    International Nuclear Information System (INIS)

    Meister, H.; Fischer, R.; Horton, L.D.; Maggi, C.F.; Nishijima, D.; Giroud, C.; Zastrow, K.-D.; Zaniol, B.

    2004-01-01

    The effective ionic charge Z eff is a means to assess the impurity content of a fusion plasma. It can be derived from measurements of bremsstrahlung intensity. These have been extended at ASDEX Upgrade by the usage of the sight lines for the charge exchange recombination diagnostic. Together with a previously installed sight line array, it is now possible to routinely determine the bremsstrahlung intensity over the whole minor radius purely from spectroscopic measurements. In a tokamak where the plasma facing components are made up of various materials, this is necessary to check if measurements are contaminated by line radiation. The bremsstrahlung background of the respective spectra is determined using Bayesian probability theory, giving consistent and improved error statistics. Using the information for electron temperature and density profiles, the Z eff profile is determined by an integrated method. The same approach to assess the Z eff profile has been demonstrated to be successful also at the JET tokamak

  9. Large Aspect Ratio Tokamak Study

    International Nuclear Information System (INIS)

    Reid, R.L.; Holmes, J.A.; Houlberg, W.A.; Peng, Y.K.M.; Strickler, D.J.; Brown, T.G.; Wiseman, G.W.

    1980-06-01

    The Large Aspect Ratio Tokamak Study (LARTS) at Oak Ridge National Laboratory (ORNL) investigated the potential for producing a viable longburn tokamak reactor by enhancing the volt-second capability of the ohmic heating transformer through the use of high aspect ratio designs. The plasma physics, engineering, and economic implications of high aspect ratio tokamaks were assessed in the context of extended burn operation. Using a one-dimensional transport code plasma startup and burn parameters were addressed. The pulsed electrical power requirements for the poloidal field system, which have a major impact on reactor economics, were minimized by optimizing the startup and shutdown portions of the tokamak cycle. A representative large aspect ratio tokamak with an aspect ratio of 8 was found to achieve a burn time of 3.5 h at capital cost only approx. 25% greater than that of a moderate aspect ratio design tokamak

  10. Inversion methods for analysis of neutron brightness measurements in tokamaks

    International Nuclear Information System (INIS)

    Gorini, G.; Gottardi, N.

    1990-02-01

    The problem of determining neutron emissivity from neutron brightness measurements in magnetic fusion plasmas is addressed. In the case of two-dimensional measurements with two orthogonal cameras, a complete, tomographic analysis of the data can in principle be performed. The results depend critically on the accuracy of the measurements and alternative solutions can be sought under the assumption of a known emissivity topology (Generalized Abel Inversion). In this work, neutron brightness data from the JET tokamak have been studied with both methods. We find that with the present experimental uncertainty (levels 10-20%) the Abel inversion method works best, while two-dimensional information cannot in general be deduced. This is confirmed by studies of the error propagation in the inversion using artificial data, which are also presented here. An important application of emissivity profile information is the determination of the plasma deuterium temperature profile, T D (R). Results are presented here from the analysis of JET data and the errors in T D (R) are discussed in some detail. It is found that, for typical JET plasma conditions, the dominant source of uncertainty arises from the high plasma impurity level and the fact that it is poorly known; these problems can be expected to be remedied and neutron brightness measurements would be expected to be very effective (especially in high density plasmas) as a T D (R) diagnostics. (author)

  11. Radial electric field in JET advanced tokamak scenarios with toroidal field ripple

    NARCIS (Netherlands)

    Crombe, K.; Andrew, Y.; Biewer, T. M.; Blanco, E.; de Vries, P. C.; Giroud, C.; Hawkes, N. C.; Meigs, A.; Tala, T.; von Hellermann, M.; Zastrow, K. D.

    2009-01-01

    A dedicated campaign has been run on JET to study the effect of toroidal field (TF) ripple on plasma performance. Radial electric field measurements from experiments on a series of plasmas with internal transport barriers (ITBs) and different levels of ripple amplitude are presented. They have been

  12. Application of a two fluid theoretical plasma transport model on current tokamak reactor designs

    International Nuclear Information System (INIS)

    Ibrahim, E.; Fowler, T.K.

    1987-06-01

    In this work, the new theoretical transport models to TIBER II design calculations are described and the results are compared with recent experimental data in large tokamaks (TFTR, JET). Tang's method is extended to a two-fluid model treating ions and electrons separately. This allows for different ion and electron temperatures, as in recent low-density experiments in TFTR, and in the TIBER II design itself. The discussion is divided into two parts: (1) Development of the theoretical transport model and (2) calibration against experiments and application to TIBER II

  13. Experience with high heat flux components in large tokamaks

    International Nuclear Information System (INIS)

    Chappuis, P.; Dietz, K.J.; Ulrickson, M.

    1991-01-01

    The large present day tokamaks. i.e.JET, TFTR, JT-60, DIII-D and Tore Supra are machines capable of sustaining plasma currents of several million amperes. Pulse durations range from a few seconds up to a minute. These large machines have been in operation for several years and there exists wide experience with materials for plasma facing components. Bare and coated metals, bare and coated graphites and beryllium were used for walls, limiters and divertors. High heat flux components are mainly radiation cooled, but stationary cooling for long pulse duration is also employed. This paper summarizes the experience gained in the large machines with respect to material selection, component design, problem areas, and plasma performance. 2 tabs., 26 figs., 50 refs

  14. EDITORIAL: Special section on recent progress on radio frequency heating and current drive studies in the JET tokamak Special section on recent progress on radio frequency heating and current drive studies in the JET tokamak

    Science.gov (United States)

    Ongena, Jef; Mailloux, Joelle; Mayoral, Marie-Line

    2009-04-01

    This special cluster of papers summarizes the work accomplished during the last three years in the framework of the Task Force Heating at JET, whose mission it is to study the optimisation of heating systems for plasma heating and current drive, launching and deposition questions and the physics of plasma rotation. Good progress and new physics insights have been obtained with the three heating systems available at JET: lower hybrid (LH), ion cyclotron resonance heating (ICRH) and neutral beam injection (NBI). Topics covered in the present issue are the use of edge gas puffing to improve the coupling of LH waves at large distances between the plasma separatrix and the LH launcher. Closely linked with this topic are detailed studies of the changes in LH coupling due to modifications in the scrape-off layer during gas puffing and simultaneous application of ICRH. We revisit the fundamental ICRH heating of D plasmas, include new physics results made possible by recently installed new diagnostic capabilities on JET and point out caveats for ITER when NBI is simultaneously applied. Other topics are the study of the anomalous behaviour of fast ions from NBI, and a study of toroidal rotation induced by ICRH, both again with possible implications for ITER. In finalizing this cluster of articles, thanks are due to all colleagues involved in preparing and executing the JET programme under EFDA in recent years. We want to thank the EFDA leadership for the special privilege of appointing us as Leaders or Deputies of Task Force Heating, a wonderful and hardworking group of colleagues. Thanks also to all other European and non-European scientists who contributed to the JET scientific programme, the Operations team of JET and the colleagues of the Close Support Unit (CSU). Thanks are also due to the Editors, Editorial Board and referees of Plasma Physics and Controlled Fusion together with the publishing staff of IOP Publishing who have supported and contributed substantially to

  15. Global sawtooth instability measured by magnetic coils in the JET tokamak

    International Nuclear Information System (INIS)

    Duperrex, P.A.; Pochelon, A.; Edwards, A.; Snipes, J.

    1992-05-01

    This paper describes measurements of the sawtooth instability in JET, in which the instability wave function is shown to extend to the edge where it is measured using magnetic coils. The numerous magnetic probes in JET allow the time evolution of the (n=0,1,2,3) toroidal Fourier components to be analysed. The n=1 magnetic component is similar to the m=1 soft X-ray centroid motion. This fact indicates the potential of edge signals in retrieving the poloidal mode spectrum of the q=m/n=1 surface. The spectrum evolution of the instability is compared for normal sawteeth (NST) and quasi-stabilised 'monster' sawteeth (MST). The spectrum is slowly decreasing with n for NST and all the components belong to one ballooning-like deformation, whereas MST show a large n=1 kink-like motion with small and independent accompanying higher n modes. Important equilibrium changes occur already during the growth of the instability and the growth rate is much faster than exponential. Both these facts imply a non-linear nature of the instability growth. Parametric dependence of growthrates, amplitudes, toroidal spectrum shape, etc., are studied to characterize the NST and MST instabilities. (author) 20 figs., 2 tabs., 46 refs

  16. Fusion potential for spherical and compact tokamaks

    International Nuclear Information System (INIS)

    Sandzelius, Mikael

    2003-02-01

    The tokamak is the most successful fusion experiment today. Despite this, the conventional tokamak has a long way to go before being realized into an economically viable power plant. In this master thesis work, two alternative tokamak configurations to the conventional tokamak has been studied, both of which could be realized to a lower cost. The fusion potential of the spherical and the compact tokamak have been examined with a comparison of the conventional tokamak in mind. The difficulties arising in the two configurations have been treated from a physical point of view concerning the fusion plasma and from a technological standpoint evolving around design, materials and engineering. Both advantages and drawbacks of either configuration have been treated relative to the conventional tokamak. The spherical tokamak shows promising plasma characteristics, notably a high β-value but have troubles with high heat loads and marginal tritium breeding. The compact tokamak operates at a high plasma density and a high magnetic field enabling it to be built considerably smaller than any other tokamak. The most notable down-side being high heat loads and neutron transport problems. With the help of theoretical reactor studies, extrapolating from where we stand today, it is conceivable that the spherical tokamak is closer of being realized of the two. But, as this study shows, the compact tokamak power plant concept offers the most appealing prospect

  17. Fusion potential for spherical and compact tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Sandzelius, Mikael

    2003-02-01

    The tokamak is the most successful fusion experiment today. Despite this, the conventional tokamak has a long way to go before being realized into an economically viable power plant. In this master thesis work, two alternative tokamak configurations to the conventional tokamak has been studied, both of which could be realized to a lower cost. The fusion potential of the spherical and the compact tokamak have been examined with a comparison of the conventional tokamak in mind. The difficulties arising in the two configurations have been treated from a physical point of view concerning the fusion plasma and from a technological standpoint evolving around design, materials and engineering. Both advantages and drawbacks of either configuration have been treated relative to the conventional tokamak. The spherical tokamak shows promising plasma characteristics, notably a high {beta}-value but have troubles with high heat loads and marginal tritium breeding. The compact tokamak operates at a high plasma density and a high magnetic field enabling it to be built considerably smaller than any other tokamak. The most notable down-side being high heat loads and neutron transport problems. With the help of theoretical reactor studies, extrapolating from where we stand today, it is conceivable that the spherical tokamak is closer of being realized of the two. But, as this study shows, the compact tokamak power plant concept offers the most appealing prospect.

  18. Runaway electron generation in tokamak disruptions

    International Nuclear Information System (INIS)

    Helander, P.; Andersson, F.; Fueloep, T.; Smith, H.; Anderson, D.; Lisak, M.; Eriksson, L.-G.

    2005-01-01

    The time evolution of the plasma current during a tokamak disruption is calculated by solving the equations for runaway electron production simultaneously with the induction equation for the toroidal electric field. The resistive diffusion time in a post-disruption plasma is typically comparable to the runaway avalanche growth time. Accordingly, the toroidal electric field induced after the thermal quench of a disruption diffuses radially through the plasma at the same time as it accelerates runaway electrons, which in turn back-react on the electric field. When these processes are accounted for in a self-consistent way, it is found that (1) the efficiency and time scale of runaway generation agrees with JET experiments; (2) the runaway current profile typically becomes more peaked than the pre-disruption current profile; and (3) can easily become radially filamented. It is also shown that higher runaway electron generation is expected if the thermal quench is sufficiently fast. (author)

  19. Detritiation studies for JET decommissioning

    Energy Technology Data Exchange (ETDEWEB)

    Perevezentsev, A.N.; Bell, A.C.; Williams, J.; Brennan, P.D. [EURATOM/UKAEA Fussion Association, Culham Science Centre, Abingdon (United Kingdom)

    2007-07-01

    JET is the world largest tokamak and has the capacity of operating with a tritium plasma. Three experimental campaigns, the Preliminary Tritium Experiment (0.1g T{sub 2}) in 1991, the Trace Tritium Experiment (5g T{sub 2}) in 2005, and the large experiment, the Deuterium-Tritium Experiment (DTE1) (100g T{sub 2}) in 1997, were carried out at JET with tritium plasmas. In DTE1 about 35 grams of tritium were fed directly into the vacuum vessel, with about 30% of this tritium being retained inside the vessel. In several years time JET will cease experimental operations and enter a decommissioning phase. In preparation for this the United Kingdom Atomic Energy Authority, the JET Operator, has been carrying out studies of various detritiation techniques. The materials which have been the subject of these studies include solid materials, such as various metals (Inconel 600 and 625, stainless steel 316L, beryllium, 'oxygen-free' copper, aluminium bronze), carbon fibre composite tiles, 'carbon' flakes and dust present in the vacuum vessel and also soft housekeeping materials. Liquid materials include organic liquids, such as vacuum oils and scintillation cocktails, and water. Detritiation of gas streams was also investigated. The purpose of the studies was to select and experimentally prove primary and auxiliary technologies for in-situ detritiation of in-vessel components and ex-situ detritiation of components removed from the vessel. The targets of ex-vessel detritiation were a reduction of the tritium inventory in and the rate of tritium out-gassing from the materials, and conversion, if possible, of intermediate level waste to low level waste and a reduction in volume of waste for disposal. The results of experimental trials and their potential application are presented. (orig.)

  20. Microwave Tokamak Experiment

    International Nuclear Information System (INIS)

    Anon.

    1988-01-01

    The Microwave Tokamak Experiment, now under construction at the Laboratory, will use microwave heating from a free-electron laser. The intense microwave pulses will be injected into the tokamak to realize several goals, including a demonstration of the effects of localized heat deposition within magnetically confined plasma, a better understanding of energy confinement in tokamaks, and use of the new free-electron laser technology for plasma heating. The experiment, soon to be operational, provides an opportunity to study dense plasmas heated by powers unprecedented in the electron-cyclotron frequency range required by the especially high magnetic fields used with the MTX and needed for reactors. 1 references, 5 figures, 3 tables

  1. Advanced Tokamak Stability Theory

    Science.gov (United States)

    Zheng, Linjin

    2015-03-01

    The intention of this book is to introduce advanced tokamak stability theory. We start with the derivation of the Grad-Shafranov equation and the construction of various toroidal flux coordinates. An analytical tokamak equilibrium theory is presented to demonstrate the Shafranov shift and how the toroidal hoop force can be balanced by the application of a vertical magnetic field in tokamaks. In addition to advanced theories, this book also discusses the intuitive physics pictures for various experimentally observed phenomena.

  2. Hamiltonian theory of the ion cyclotron minority heating dynamics in tokamak plasmas

    International Nuclear Information System (INIS)

    Becoulet, A.; Gambier, D.J.; Samain, A.

    1990-03-01

    The question of heating a tokamak plasma by means of electromagnetic waves in the Ion Cyclotron Range of Frequency (ICRF) is considered in the perspective of large RF powers and in the low collisionality regime. In such case the Quasi Linear Theory (QLT) is validated by the Hamiltonian dynamics of the wave particle interaction which exceeds the threshold of the intrinsic stochasticity. The Hamiltonian dynamics is represented by the evolution of a set of three canonical action angle variables well adapted to the tokamak magnetic configuration. This approach allows to derive the RF diffusion coefficient with very few assumptions. The distribution function of the resonant ions is written as a Fokker Planck equation but the emphasis is put on the QL diffusion instead of on the usual diffusion induced by collisions. Then the Fokker Planck equation is given a variational from which a solution is derived in the form of a semi analytical trial function of three parameters: the percentage of resonant particle contained in the tail; an isotropic width ΔT and an anisotropic one ΔP. This solution is successfully tested against real experimental observations. Practically it is shown that in the case of JET the distribution function is influenced by adiabatic barriers which in turn limit the Hamiltonian stochasticity domain within energy values typically in the MeV range. Consequently and for a given ICRF power, the tail energy excursion is lower and its concentration higher than that of a bounce averaged prediction. This may actually be an advantage for machines like JET considering the energy range required to simulate the α-particle behaviour in a relevant fusion reactor

  3. Integrated modelling of material migration and target plate power handling at JET

    International Nuclear Information System (INIS)

    Coster, D.P.; Bonnin, X.; Chankin, A.

    2005-01-01

    The complexity of the tokamak edge and scrape-off layer (SOL) region is such that extrapolation to ITER requires modelling to be pursued through the integration of a number of edge codes, each of which must be thoroughly tested against results from present day machines. This contribution demonstrates how the edge modelling effort at JET is focused on such an approach by considering two examples, target power loading and material erosion and migration, the understanding of which are crucial issues for ITER. (author)

  4. Proceedings of the workshop of three large tokamak cooperation on energy confinement scaling under intensive auxiliary heating, May 18 ∼ 20, 1992, Naka

    International Nuclear Information System (INIS)

    1992-09-01

    The workshop of three large tokamak cooperation W22 on 'Energy confinement scaling under intensive auxiliary heating' was held 18-20 May, 1992, at Naka Fusion Research Establishment. This proceedings compiles 14 synopses of contributions (5 from JET, 4 from JT-60, 3 from TFTR, and 1 each from DIII-D JFT-2M) and the summary of the workshop. Topic sections are ; (i) L-mode confinement and scaling, (ii) Confinement at high β P regimes, Supershots, High poloidal beta enhanced confinement mode etc., (iii) Confinement at various H-mode regimes and scaling (including the VH-mode), (iv) Characteristic time scales for present tokamak regimes, and (v) Theoretical comparison with experimental data. (author)

  5. Overview of JET results, near term plans

    Energy Technology Data Exchange (ETDEWEB)

    Pamela, J.; Rapp, J

    2003-09-01

    In preparation of ITER operation the JET programme has been focussed to consolidate the ITER reference scenario, the ELMy H-mode, and furthermore to mature the Advanced Tokamak Scenarios, candidate for steady state operation on ITER. In type-I ELMy H-modes simultaneously high confinement (f{sub H98}{approx}1) and high densities (n/n{sup GW}>0.85) were achieved in stationary conditions by several techniques: (a) increasing plasma triangularity (close to ITER values), (b) argon seeding and (c) periodic pellet fuelling. Techniques for controlling high-pressure operation (control of neoclassical tearing modes (NTM)) and improving amelioration of transient divertor heat loads due to ELMs have been elaborated. In Advanced Tokamak Scenarios the improvement of LHCD coupling to the plasma led to reversed shear plasmas, providing reliable access to strong Internal Transport barriers (ITBs) at lower auxiliary heating powers. The successful development of real-time feedback schemes allowed ITBs to be controlled in steady state conditions (7.5 s, 27x{tau}{sub E}). In particular the capability to control both the pressure and current profiles has been demonstrated. Studies related to in-vessel material migration have been further extended, in particular with a new quartz-micro balance diagnostic, further tile analysis and an experimental campaign in helium. This led to new insights, underlining the importance of carbon erosion in the main chamber and chemical erosion in the inner divertor on JET. Altogether this might enable the control of Tritium co-deposition. Detritiation technologies are being developed which could find application on ITER. Enhancements of the facility are undertaken, in view of further extending the operational range closer to ITER, thereby supporting the optimisation of ITER operating scenarios and of ITER auxiliaries.

  6. Alfven Spectroscopy for Advanced Scenarios on JET

    International Nuclear Information System (INIS)

    Sharapov, S. E.

    2007-01-01

    Advanced tokamak scenarios on JET exhibit outstanding quality fusion-grade plasmas, with internal transport barriers (ITBs) capable of supporting gradients ∇ T i ≅ 150 keV/m (with T i (0)≅ 40 keV), and with ) q(r) -profiles ranging from monotonic to deep shear reversal, including the limiting case of toroidal current holes. It was found experimentally, that in reversed shear JET discharges the ITB start from so-called ITB triggering events, which are seen as increases in electron temperature within, e.g. r/a ≤ 0.4 by Δ T e /T e ∼ 10-30%. If main heating power is applied at this time, an ITB is formed easily. Without an extra-heating power the improved confinement effect is lost in about 100 msec. Here, we investigate the magnetic field topology at the time of the ITB triggering events in JET plasmas. Alfven spectroscopy based on discrete spectrum of Alfven eigenmodes (AEs) excited by ICRH-accelerated and/or NBI-produced energetic ions is used for determining the evolution of the q(r)- profiles. Recently developed interferometry diagnostics of AEs significantly extended time resolution and sensitivity of Alfven spectroscopy on JET and made it possible to perform the ITB triggering event studies with a high accuracy. The ITB triggering events are found to occur when q m in (t) passes values q m ininteger (majority of the cases), q m in= half-integer, and when q(r=0)--∞ (current hole is triggered). This experimental data is compared to the idensity of rational surfaces transport theory. (Author)

  7. Sputtering measurements on JET using a multichannel visible spectrometer

    International Nuclear Information System (INIS)

    Stamp, M.F.; Morgan, P.D.; Summers, H.P.

    1989-01-01

    A multichannel visible spectrometer has been used on JET to simultaneously observe the emission from D, H, C and O atoms and ions in the proximity of a belt limiter. The absolute intensity of the line emission, along with a Langmuir probe measurement of the edge electron temperature and an atomic physics model, allows us to calculate the influxes of these species. Under steady-state conditions the influxes of D and He are the same as the effluxes, so the ratio of impurity to fuel fluxes, e.g. carbon to deuterium, is the apparent sputtering yield of deuterium on carbon in the tokamak environment. The measured flux ratio Γ c /Γ D is also indicative of the central carbon impurity concentration in JET, because the limiters are the main source of impurities. For similar particle transport, Γ c /Γ D =n c (o)/n D (o), so for a 10% flux ratio, n c /n e =6.6%, Z eff =3. (author) 7 refs., 5 figs

  8. Technical aspects of the joint JET-ISX-B beryllium limiter experiment

    International Nuclear Information System (INIS)

    Edmonds, P.H.; Dietz, K.J.; Mioduszewski, P.K.; Watson, R.D.; Emerson, L.C.; Gabbard, W.A.; Goodall, D.; Simpkins, J.E.; Yarber, J.L.

    1985-01-01

    An experiment has been performed on the Impurity Study Experiment (ISX-B) tokamak to test beryllium as a limiter material. Beryllium is an attractive candidate for a limiter and has been proposed for use in the Joint European Torus (JET) experiment. A temperature-controlled, segmented, beryllium top-rail limiter was located inside the plasma radius described by the existing titanium limiters. An extended set of diagnostics was added for measurement of scrapeoff and limiter parameters. These included visible and infrared monitoring systems, probes, and surface analysis experiments. Tokamak experiments included parameter surveys of both Ohmically heated and neutral-beam-heated plasmas and an extended fluence test of the limiter. The most significant effect of operation with a beryllium limiter was the reduction in low-Z impurities caused by gettering action of beryllium deposited on the liner walls. The experiment required the design and implementation of contamination control apparatus and work procedures to prevent the accidental dispersion of beryllium dust

  9. Burning plasma simulation and environmental assessment of tokamak, spherical tokamak and helical reactors

    International Nuclear Information System (INIS)

    Yamazaki, K.; Uemura, S.; Oishi, T.; Arimoto, H.; Shoji, T.; Garcia, J.

    2009-01-01

    Reference 1-GWe DT reactors (tokamak TR-1, spherical tokamak ST-1 and helical HR-1 reactors) are designed using physics, engineering and cost (PEC) code, and their plasma behaviours with internal transport barrier operations are analysed using toroidal transport analysis linkage (TOTAL) code, which clarifies the requirement of deep penetration of pellet fuelling to realize steady-state advanced burning operation. In addition, economical and environmental assessments were performed using extended PEC code, which shows the advantage of high beta tokamak reactors in the cost of electricity (COE) and the advantage of compact spherical tokamak in life-cycle CO 2 emission reduction. Comparing with other electric power generation systems, the COE of the fusion reactor is higher than that of the fission reactor, but on the same level as the oil thermal power system. CO 2 reduction can be achieved in fusion reactors the same as in the fission reactor. The energy payback ratio of the high-beta tokamak reactor TR-1 could be higher than that of other systems including the fission reactor.

  10. Introducing minimum Fisher regularisation tomography to AXUV and soft x-ray diagnostic systems of the COMPASS tokamak

    International Nuclear Information System (INIS)

    Mlynar, J.; Weinzettl, V.; Imrisek, M.; Odstrcil, M.; Havlicek, J.; Janky, F.; Alper, B.; Murari, A.

    2012-01-01

    The contribution focuses on plasma tomography via the minimum Fisher regularisation (MFR) algorithm applied on data from the recently commissioned tomographic diagnostics on the COMPASS tokamak. The MFR expertise is based on previous applications at Joint European Torus (JET), as exemplified in a new case study of the plasma position analyses based on JET soft x-ray (SXR) tomographic reconstruction. Subsequent application of the MFR algorithm on COMPASS data from cameras with absolute extreme ultraviolet (AXUV) photodiodes disclosed a peaked radiating region near the limiter. Moreover, its time evolution indicates transient plasma edge cooling following a radial plasma shift. In the SXR data, MFR demonstrated that a high resolution plasma positioning independent of the magnetic diagnostics would be possible provided that a proper calibration of the cameras on an x-ray source is undertaken.

  11. Tokamak control simulator

    International Nuclear Information System (INIS)

    Edelbaum, T.N.; Serben, S.; Var, R.E.

    1976-01-01

    A computer model of a tokamak experimental power reactor and its control system is being constructed. This simulator will allow the exploration of various open loop and closed loop strategies for reactor control. This paper provides a brief description of the simulator and some of the potential control problems associated with this class of tokamaks

  12. Regime of very high confinement in the boronized DIII-D tokamak

    International Nuclear Information System (INIS)

    Jackson, G.L.; Winter, J.; Taylor, T.S.; Burrell, K.H.; DeBoo, J.C.; Greenfield, C.M.; Groebner, R.J.; Hodapp, T.; Holtrop, K.; Lazarus, E.A.; Lao, L.L.; Lippmann, S.I.; Osborne, T.H.; Petrie, T.W.; Phillips, J.; James, R.; Schissel, D.P.; Strait, E.J.; Turnbull, A.D.; West, W.P.; DIII-D Team

    1991-01-01

    Following boronization, tokamak discharges in DIII-D have been obtained with confinement times up to a factor of 3.5 above the ITER89-P L-mode scaling and 1.8 times greater than the DIII-D/JET H-mode scaling relation. Very high confinement phases are characterized by relatively high central density with n e (0)∼1x10 20 m -3 , and central ion temperatures up to 13.6 keV at moderate plasma currents (1.6 MA) and heating powers (12.5--15.3 MW). These discharges exhibit a low fraction of radiated power, P≤25%, Z eff (0) close to unity, and lower impurity influxes than comparable DIII-D discharges before boronization

  13. Survey of Tokamak experiments

    International Nuclear Information System (INIS)

    Bickerton, R.J.

    1977-01-01

    The survey covers the following topics:- Introduction and history of tokamak research; review of tokamak apparatus, existing and planned; remarks on measurement techniques and their limitations; main results in terms of electron and ion temperatures, plasma density, containment times, etc. Empirical scaling; range of operating densities; impurities, origin, behaviour and control (including divertors); data on fluctuations and instabilities in tokamak plasmas; data on disruptive instabilities; experiments on shaped cross-sections; present experimental evidence on β limits; auxiliary heating; experimental and theoretical problems for the future. (author)

  14. Tokamak building-design considerations for a large tokamak device

    International Nuclear Information System (INIS)

    Barrett, R.J.; Thomson, S.L.

    1981-01-01

    Design and construction of a satisfactory tokamak building to support FED appears feasible. Further, a pressure vessel building does not appear necessary to meet the plant safety requirements. Some of the building functions will require safety class systems to assure reliable and safe operation. A rectangular tokamak building has been selected for FED preconceptual design which will be part of the confinement system relying on ventilation and other design features to reduce the consequences and probability of radioactivity release

  15. Modelling of Ohmic discharges in ADITYA tokamak using the Tokamak Simulation Code

    International Nuclear Information System (INIS)

    Bandyopadhyay, I; Ahmed, S M; Atrey, P K; Bhatt, S B; Bhattacharya, R; Chaudhury, M B; Deshpande, S P; Gupta, C N; Jha, R; Joisa, Y Shankar; Kumar, Vinay; Manchanda, R; Raju, D; Rao, C V S; Vasu, P

    2004-01-01

    Several Ohmic discharges of the ADITYA tokamak are simulated using the Tokamak Simulation Code (TSC), similar to that done earlier for the TFTR tokamak. Unlike TFTR, the dominant radiation process in ADITYA is through impurity line radiation. TSC can follow the experimental plasma current and position to very good accuracy. The thermal transport model of TSC including impurity line radiation gives a good match of the simulated results with experimental data for the Ohmic flux consumption, electron temperature and Z eff . Even the simulated magnetic probe signals are in reasonably good agreement with the experimental values

  16. Modelling of Ohmic discharges in ADITYA tokamak using the Tokamak Simulation Code

    Energy Technology Data Exchange (ETDEWEB)

    Bandyopadhyay, I; Ahmed, S M; Atrey, P K; Bhatt, S B; Bhattacharya, R; Chaudhury, M B; Deshpande, S P; Gupta, C N; Jha, R; Joisa, Y Shankar; Kumar, Vinay; Manchanda, R; Raju, D; Rao, C V S; Vasu, P [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)

    2004-09-01

    Several Ohmic discharges of the ADITYA tokamak are simulated using the Tokamak Simulation Code (TSC), similar to that done earlier for the TFTR tokamak. Unlike TFTR, the dominant radiation process in ADITYA is through impurity line radiation. TSC can follow the experimental plasma current and position to very good accuracy. The thermal transport model of TSC including impurity line radiation gives a good match of the simulated results with experimental data for the Ohmic flux consumption, electron temperature and Z{sub eff}. Even the simulated magnetic probe signals are in reasonably good agreement with the experimental values.

  17. Advanced commercial tokamak study

    International Nuclear Information System (INIS)

    Thomson, S.L.; Dabiri, A.E.; Keeton, D.C.; Brown, T.G.; Bussell, G.T.

    1985-12-01

    Advanced commercial tokamak studies were performed by the Fusion Engineering Design Center (FEDC) as a participant in the Tokamak Power Systems Studies (TPSS) project coordinated by the Office of Fusion Energy. The FEDC studies addressed the issues of tokamak reactor cost, size, and complexity. A scoping study model was developed to determine the effect of beta on tokamak economics, and it was found that a competitive cost of electricity could be achieved at a beta of 10 to 15%. The implications of operating at a beta of up to 25% were also addressed. It was found that the economics of fusion, like those of fission, improve as unit size increases. However, small units were found to be competitive as elements of a multiplex plant, provided that unit cost and maintenance time reductions are realized for the small units. The modular tokamak configuration combined several new approaches to develop a less complex and lower cost reactor. The modular design combines the toroidal field coil with the reactor structure, locates the primary vacuum boundary at the reactor cell wall, and uses a vertical assembly and maintenance approach. 12 refs., 19 figs

  18. D-D tokamak reactor assessment

    International Nuclear Information System (INIS)

    Baxter, D.C.; Dabiri, A.E.

    1983-01-01

    A quantitative comparison of the physics and technology requirements, and the cost and safety performance of a d-d tokamak relative to a d-t tokamak has been performed. The first wall/blanket and energy recovery cycle for the d-d tokamak is simpler, and has a higher efficiency than the d-t tokamak. In most other technology areas (such as magnets, RF, vacuum, etc.) d-d requirements are more severe and the systems are more complex, expensive and may involve higher technical risk than d-t tokamak systems. Tritium technology for processing the plasma exhaust, and tritium refueling technology are required for d-d reactors, but no tritium containment around the blanket or heat transport system is needed. Cost studies show that for high plasma beta and high magnetic field the cost of electricity from d-d and d-t tokamaks is comparable. Safety analysis shows less radioactivity in a d-d reactor but larger amounts of stored energy and thus higher potential for energy release. Consequences of all postulated d-d accidents are significantly smaller than those from d-t reactor tritium releases

  19. Magnetic Measuring Instrumentation with Radiation-Resistant Hall Sensors for Fusion Reactors: Experience of Testing at JET

    Czech Academy of Sciences Publication Activity Database

    Bolshakova, I.; Quercia, A.; Coccorese, V.; Murari, A.; Holyaka, R.; Ďuran, Ivan; Viererbl, L.; Konopleva, R.; Yerashok, V.

    2012-01-01

    Roč. 59, č. 4 (2012), s. 1224-1231 ISSN 0018-9499. [International Conference on Advancements in Nuclear Instrumentation, Measurement Methods and their Applications. Ghent, 06.06.2011-09.06.2011] R&D Projects: GA ČR GAP205/10/2055 Institutional research plan: CEZ:AV0Z20430508 Keywords : plasma * tokamak * JET * Hall probes * radiation resistance Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.219, year: 2012

  20. Observation and explanation of the JET n=0 chirping mode

    Energy Technology Data Exchange (ETDEWEB)

    Boswell, C.J. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)]. E-mail: christopher.boswell@navy.mil; Berk, H.L. [Institute for Fusion Studies, University of Texas at Austin, Austin, TX 78712-1060 (United States); Borba, D.N. [Centro de Fusao Nuclear Associacao Euratom-IST, Instituto Superior Tecnico, 1049001 Lisbon (Portugal); EFDA Close Support Unit, Culham Science Centre, OX14 3DB (United Kingdom); Johnson, T. [Alfven Laboratory, KTH, Euratom-VR Association (Sweden); Pinches, S.D. [Max-Planck Institute for Plasma Physics, EURATOM Association, D-85748 Garching (Germany); Sharapov, S.E. [Euratom-UKAEA Fusion Association, Culham Science Centre, Abingdon OX14 3DB (United Kingdom)

    2006-10-09

    Persistent rapid up and down frequency chirping modes with a toroidal mode number of zero (n=0) have been observed in the JET tokamak when energetic ions, with a mean energy {approx}500keV, were created by high field side ion cyclotron resonance frequency heating. This heating method enables the formation of an energetically inverted ion distribution function that allows ions to spontaneously excite the observed instability, identified as a global geodesic acoustic mode. The interpretation is that phase space structures form and interact with the fluid zonal flow to produce the pronounced frequency chirping.

  1. Design, implementation and test of the XSC extreme shape controller in JET

    International Nuclear Information System (INIS)

    Albanese, R.; Ambrosino, G.; Ariola, M.; Cenedese, A.; Crisanti, F.; Tommasi, G. De; Mattei, M.; Piccolo, F.; Pironti, A.; Sartori, F.; Villone, F.

    2005-01-01

    A new model-based plasma current and shape controller has been set up and tested on the JET Tokamak with the existing active circuits and control. The installation has been carried out without causing any interference to the plasma operation and without requiring a long commissioning time. Eventually, the new controller was used on really extremely shaped internal transport barrier experiments at high poloidal beta and in the presence of quite large variations of the plasma current density profile (variation range Δβ pol up to 1.5 and Δl i up to 0.5). The extreme shape controller (XSC) controller architecture and philosophy also offer new interesting opportunities, e.g., the separatrix sweeping on the divertor plates without significantly affecting the overall plasma shape, and the possibility of improving the overall tokamak performance via combined control of plasma shape, current and profile. The adopted methodology constitutes also an important test bed for feedback control strategies of ITER relevance

  2. Summary discussion: An integrated advanced tokamak reactor

    International Nuclear Information System (INIS)

    Sauthoff, N.R.

    1994-01-01

    The tokamak concept improvement workshop addressed a wide range of issues involved in the development of a more attractive tokamak. The agenda for the workshop progressed from a general discussion of the long-range energy context (with the objective being the identification of a set of criteria and ''figures of merit'' for measuring the attractiveness of a tokamak concept) to particular opportunities for the improvement of the tokamak concept. The discussions concluded with a compilation of research program elements leading to an improved tokamak concept

  3. Energetics of turbulent transport processes in tokamaks

    International Nuclear Information System (INIS)

    Haas, F.A.; Thyagaraja, A.

    1987-01-01

    The effect of electromagnetic turbulence on electrons and ions under Tokamak conditions is considered using a kinetic description. Taking the magnetic fluctuation spectrum as given, the density fluctuation spectrum is self-consistently calculated taking account of quasi-neutrality. The calculation is valid for arbitrary collisionality and appropriate to low frequencies typical of experiment. In addition to the usual enhancement of the radial electron energy transport, it is found that the turbulent fluctuations can heat the plasma at rates comparable to ordinary ohmic heating under well-defined conditions. Interestingly, electromagnetic turbulence appears to imply only an insignificant correction to the toroidal resistance of the plasma as estimated from Spitzer resistivity. The scalings of anomalous transport, fluctuations and heating with temperature and plasma volume are investigated. The assumption that the magnetic fluctuation spectrum of the turbulence is invariant under a wide range of conditions is shown to result in interesting consequences for JET-like plasmas. (author)

  4. JET neutral beam duct Optical Interlock

    Energy Technology Data Exchange (ETDEWEB)

    Ash, A.D.; Jones, T.T.C.; Surrey, E.; Ćirić, D.; Hall, S.I.; Young, D.; Afzal, M.; Hackett, L.; Day, I.E.; King, R.

    2015-10-15

    Highlights: • Optical Interlocks were installed on the JET NBI system as part of the EP2 upgrade. • The system protects the JET tokamak and NBI systems from thermal load damage. • Balmer-α beam emission is used to monitor the neutral beam-line pressure. • We demonstrate an improved trip delay of 2 ms compared to 50 ms before EP2. - Abstract: The JET Neutral Beam Injection (NBI) system is the most powerful neutral beam plasma heating system currently operating. Optical Interlocks were installed on the beam lines in 2011 for the JET Enhancement Project 2 (EP2), when the heating power was increased from 23 MW to 34 MW. JET NBI has two beam lines. Each has eight positive ion injectors operating in deuterium at 80 kV–125 kV (accelerator voltage) and up to 65 A (beam current). Heating power is delivered through two ducts where the central power density can be more than 100 MW/m{sup 2}. In order to deliver this safely, the beam line pressure should be below 2 × 10{sup −5} mbar otherwise the power load on the duct from the re-ionised fraction of the beam is excessive. The new Optical Interlock monitors the duct pressure by measuring the Balmer-α beam emission (656 nm). This is proportional to the instantaneous beam flux and the duct pressure. Light is collected from a diagnostic window and focused into 1-mm diameter fibres. The Doppler shifted signal is selected using an angle-tuned interference filter. The light is measured by a photo-multiplier module with a logarithmic amplifier. The interlock activation time of 2 ms is sufficient to protect the system from a fully re-ionised beam—a significant improvement on the previous interlock. The dynamic range is sufficient to see bremsstrahlung emission from JET plasma and not saturate during plasma disruptions. For high neutron flux operations the optical fibres within the biological shield can be annealed to 350 °C. A self-test is possible by illuminating the diagnostic window with a test lamp and measuring

  5. Alfven Spectroscopy for Advanced Scenarios on JET

    Energy Technology Data Exchange (ETDEWEB)

    Sharapov, S. E.

    2007-07-01

    Advanced tokamak scenarios on JET exhibit outstanding quality fusion-grade plasmas, with internal transport barriers (ITBs) capable of supporting gradients {nabla} T{sub i}{approx_equal} 150 keV/m (with T{sub i}(0){approx_equal} 40 keV), and with q(r)-profiles ranging from monotonic to deep shear reversal, including the limiting case of toroidal current holes. It was found experimentally, that in reversed shear JET discharges the ITB start from so-called ITB triggering events, which are seen as increases in electron temperature within, e.g. r/a {<=} 0.4 by {delta} T{sub e}/T{sub e}{approx} 10-30%. If main heating power is applied at this time, an ITB is formed easily. Without an extra-heating power the improved confinement effect is lost in about 100 msec. Here, we investigate the magnetic field topology at the time of the ITB triggering events in JET plasmas. Alfven spectroscopy based on discrete spectrum of Alfven eigenmodes (AEs) excited by ICRH-accelerated and/or NBI-produced energetic ions is used for determining the evolution of the q(r)- profiles. Recently developed interferometry diagnostics of AEs significantly extended time resolution and sensitivity of Alfven spectroscopy on JET and made it possible to perform the ITB triggering event studies with a high accuracy. The ITB triggering events are found to occur when q{sub min} (t) passes values q{sub min} integer (majority of the cases), q{sub min}= half-integer, and when q(r=0)--infinity (current hole is triggered). This experimental data is compared to the density of rational surfaces transport theory. (Author)

  6. Conceptual Design for a Bulk Tungsten Divertor Tile in JET

    International Nuclear Information System (INIS)

    Mertens, P.; Neubauer, O.; Philipps, V.; Schweer, B.; Samm, U.; Hirai, T.; Sadakov, S.

    2006-01-01

    With ITER on the verge of being build, the ITER-like Wall project (ILW) for JET aims at providing the plasma chamber of the tokamak with an environment of mixed materials which will be relevant to the support of decisions to the first wall construction and, from the point of view of plasma physics, to the corresponding investigations of possible plasma configuration and plasma-wall interaction. In both respects, tungsten plays a key role in the divertor cladding whereas beryllium will be used for the vessel's first wall. For the central tile, also called LB-SRP for '' Load-Bearing Septum Replacement Plate '', resort to bulk tungsten is envisaged in order to cope with the high loads expected (up to 10 MW/m 2 for about 10 s). This is indeed the preferred plasma-facing component for positioning the outer strike-point in the divertor. Forschungszentrum Juelich has developed a conceptual design for this tile, based on an assembly of tungsten blades or lamellae. It was selected in the frame of an extensive R-and-D study in search of a suitable, inertially cooled component(T. Hirai et al., R-and-D on full tungsten divertor and beryllium wall for JET ITER-like Wall Project: this conference). As reported elsewhere, the design is actually driven by electromagnetic considerations in the first place(S. Sadakov et al., Detailed electromagnetic analysis for optimisation of a tungsten divertor plate for JET: this conference). The lamellae are grouped in four stacks per tile which are independently attached to an equally re-designed supporting structure. A so-called adapter plate, also a new design, takes care of an appropriate interface to the base carrier of JET, onto which modules of two tiles are positioned and screwed by remote handling (RH) procedures. The compatibility of the design on the whole with RH requirements is another essential ingredient which was duly taken into account throughout. The concept and the underlying philosophy will be presented along with important

  7. Long Term Tritium Trapping in TFTR and JET

    International Nuclear Information System (INIS)

    Skinner, C.H.; Gentile, C.A.; Young, K.M.; Coad, J.P.; Hogan, J.T.; Penzhorn, R.-D.; Bekris, N.

    2001-01-01

    Tritium retention in TFTR [Tokamak Fusion Test Reactor] and JET [Joint European Torus] shows striking similarities and contrasts. In TFTR, 5 g of tritium were injected into circular plasmas over a 3.5 year period, mostly by neutral-beam injection. In JET, 35 g were injected into divertor plasmas over a 6 month campaign, mostly by gas puffing. In TFTR, the bumper limiter provided a large source of eroded carbon and a major part of tritium was co-deposited on the limiter and vessel wall. Only a small area of the co-deposit flaked off. In JET, the wall is a net erosion area, and co-deposition occurs principally in shadowed parts of the inner divertor, with heavy flaking. In both machines, the initial tritium retention, after a change from deuterium [D] to tritium [T] gas puffing, is high and is due to isotope exchange with deuterium on plasma-facing surfaces (dynamic inventory). The contribution of co-deposition is lower but cumulative, and is revealed by including periods of D fueling that reversed the T/D isotope exchange. Ion beam analysis of flakes from TFTR showed an atomic D/C ratio of 0.13 on the plasma facing surface, 0.25 on the back surface and 0.11 in the bulk. Data from a JET divertor tile showed a larger D/C ratio with 46% C, 30% D, 20% H and 4% O. Deuterium, tritium, and beryllium profiles have been measured and show a thin less than 50 micron co-deposited layer. Flakes retrieved from the JET vacuum vessel exhibited a high tritium release rate of 2e10 Bq/month/g. BBQ modeling of the effect of lithium on retention in TFTR showed overlapping lithium and tritium implantation and a 1.3x increase in local T retention

  8. Progress of the ECH·ECCD experiments. Research progress of the ECH·ECCD experiments in tokamaks and spherical tokamaks

    International Nuclear Information System (INIS)

    Isayama, Akihiko; Tanaka, Hitoshi

    2009-01-01

    Recent progress in the ECH·ECCD study in tokamak and spherical tokamak devices is described. As for the tokamak study, results on the control of neoclassical tearing modes and sawtooth oscillations, the current profile, the internal transport barrier, the plasma start-up and the discharge cleaning are given. As for the spherical tokamak study, the plasma start-up by ECH·ECCD and the electron-Bernstein-wave heating and the current drive are described. (T.I.)

  9. Characterization of plasma current quench at JET

    International Nuclear Information System (INIS)

    Riccardo, V; Barabaschi, P; Sugihara, M

    2005-01-01

    Eddy currents generated during the fastest disruption current decays represent the most severe design condition for medium and small size in-vessel components of most tokamaks. Best-fit linear and instantaneous plasma current quench rates have been extracted for a set of recent JET disruptions. Contrary to expectations, the current quench rate spectrum of high and low thermal energy disruptions is not substantially different. For most of the disruptions with the highest instantaneous current quench rate an exponential fit of the early phase of the current decay provides a more accurate estimate of the maximum current decay velocity. However, this fit is only suitable to model the fastest events, for which the current quench is dominated by radiation losses rather than the plasma motion

  10. Preliminary Design of Alborz Tokamak

    Science.gov (United States)

    Mardani, M.; Amrollahi, R.; Saramad, S.

    2012-04-01

    The Alborz tokamak is a D-shape cross section tokamak that is under construction in Amirkabir University of Technology. The most important part of the tokamak design is the design of TF coils. In this paper a refined design of the TF coil system for the Alborz tokamak is presented. This design is based on cooper cable conductor with 5 cm width and 6 mm thickness. The TF coil system is consist of 16 rectangular shape coils, that makes the magnetic field of 0.7 T at the plasma center. The stored energy in total is 160 kJ, and the power supply used in this system is a capacitor bank with capacity of C = 1.32 mF and V max = 14 kV.

  11. Feasibility study for a multi-channel pulsed radar reflectometer for the jet divertor region

    International Nuclear Information System (INIS)

    Heijnen, S.H.; Pol, M.J. van de.

    1994-09-01

    In this report, the feasibility of a pulsed radar system for measuring the electron density profile in the divertor region of JET is studied. Some dedicated experiments are performed with a four-channel system, which was designed for the Rijnhuizen Tokamak Project. To simulate divertor plasmas the measurements are performed in ECRH induced plasmas without current. The parameters of these kinds of plasmas are: n e 19 m -3 , T e <100 eV, and a diameter of ∼30 cm. (HSI)

  12. Moving Divertor Plates in a Tokamak

    International Nuclear Information System (INIS)

    Zweben, S.J.; Zhang, H.

    2009-01-01

    Moving divertor plates could help solve some of the problems of the tokamak divertor through mechanical ingenuity rather than plasma physics. These plates would be passively heated on each pass through the tokamak and cooled and reprocessed outside the tokamak. There are many design options using varying plate shapes, orientations, motions, coatings, and compositions

  13. Moving Divertor Plates in a Tokamak

    Energy Technology Data Exchange (ETDEWEB)

    S.J. Zweben, H. Zhang

    2009-02-12

    Moving divertor plates could help solve some of the problems of the tokamak divertor through mechanical ingenuity rather than plasma physics. These plates would be passively heated on each pass through the tokamak and cooled and reprocessed outside the tokamak. There are many design options using varying plate shapes, orientations, motions, coatings, and compositions.

  14. Contribution to the multi-machine pedestal scaling from the COMPASS tokamak

    Science.gov (United States)

    Komm, M.; Bílková, P.; Aftanas, M.; Berta, M.; Böhm, P.; Bogár, O.; Frassinetti, L.; Grover, O.; Háček, P.; Havlicek, J.; Hron, M.; Imríšek, M.; Krbec, J.; Mitošínková, K.; Naydenkova, D.; Pánek, R.; Peterka, M.; Snyder, P. B.; Stefanikova, E.; Stöckel, J.; Sos, M.; Urban, J.; Varju, J.; Vondráček, P.; Weinzettl, V.; the COMPASS Team

    2017-05-01

    First systematic measurements of pedestal structure during Ohmic and NBI-assisted Type I ELMy H-modes were performed on the COMPASS tokamak in two dedicated experimental campaigns during 2015 and 2016. By adjusting the NBI heating and a toroidal magnetic field, the electron pedestal temperature was increased from 200 eV up to 300 eV, which allowed reaching pedestal collisionality ν \\text{ped}\\ast   <  1 at q95 ~3. COMPASS has approached conditions for the Identity experiment done at JET & DIII-D, complementing the range of scanned ρ \\text{ped}\\ast . The pedestal pressure was successfully reproduced by the EPED model. The dependence of pedestal pressure width on ν \\text{ped}\\ast and β \\text{ped ~ }\\text{pol} is discussed.

  15. The ARIES tokamak reactor study

    International Nuclear Information System (INIS)

    1989-10-01

    The ARIES study is a community effort to develop several visions of tokamaks as fusion power reactors. The aims are to determine the potential economics, safety, and environmental features of a range of possible tokamak reactors, and to identify physics and technology areas with the highest leverage for achieving the best tokamak reactor. Three ARIES visions are planned, each having a different degree of extrapolation from the present data base in physics and technology. The ARIES-I design assumes a minimum extrapolation from current tokamak physics (e.g., 1st stability) and incorporates technological advances that can be available in the next 20 to 30 years. ARIES-II is a DT-burning tokamak which would operate at a higher beta in the 2nd MHD stability regime. It employs both potential advances in the physics and expected advances in technology and engineering. ARIES-II will examine the potential of the tokamak and the D 3 He fuel cycle. This report is a collection of 14 papers on the results of the ARIES study which were presented at the IEEE 13th Symposium on Fusion Engineering (October 2-6, 1989, Knoxville, TN). This collection describes the ARIES research effort, with emphasis on the ARIES-I design, summarizing the major results, the key technical issues, and the central conclusions

  16. JET experiments with tritium and deuterium–tritium mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Horton, Lorne, E-mail: Lorne.Horton@jet.uk [JET Exploitation Unit, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); European Commission, B-1049 Brussels (Belgium); EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Batistoni, P. [Unità Tecnica Fusione - ENEA C. R. Frascati - via E. Fermi 45, Frascati (Roma), 00044, Frascati (Italy); EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Boyer, H.; Challis, C.; Ćirić, D. [CCFE, Culham Science Centre, Abingdon OX14 3DB, Oxon (United Kingdom); EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Donné, A.J.H. [EUROfusion Programme Management Unit, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); FOM Institute DIFFER, PO Box 1207, NL-3430 BE Nieuwegein (Netherlands); EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Eriksson, L.-G. [European Commission, B-1049 Brussels (Belgium); EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Garcia, J. [CEA, IRFM, F-13108 Saint Paul Lez Durance (France); EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Garzotti, L.; Gee, S. [CCFE, Culham Science Centre, Abingdon OX14 3DB, Oxon (United Kingdom); EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Hobirk, J. [Max-Planck-Institut für Plasmaphysik, D-85748 Garching (Germany); EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Joffrin, E. [CEA, IRFM, F-13108 Saint Paul Lez Durance (France); EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); and others

    2016-11-01

    Highlights: • JET is preparing for a series of experiments with tritium and deuterium–tritium mixtures. • Physics objectives include integrated demonstration of ITER operating scenarios, isotope and alpha physics. • Technology objectives include neutronics code validation, material studies and safety investigations. • Strong emphasis on gaining experience in operation of a nuclear tokamak and training scientists and engineers for ITER. - Abstract: Extensive preparations are now underway for an experiment in the Joint European Torus (JET) using tritium and deuterium–tritium mixtures. The goals of this experiment are described as well as the progress that has been made in developing plasma operational scenarios and physics reference pulses for use in deuterium–tritium and full tritium plasmas. At present, the high performance plasmas to be tested with tritium are based on either a conventional ELMy H-mode at high plasma current and magnetic field (operation at up to 4 MA and 4 T is being prepared) or the so-called improved H-mode or hybrid regime of operation in which high normalised plasma pressure at somewhat reduced plasma current results in enhanced energy confinement. Both of these regimes are being re-developed in conjunction with JET's ITER-like Wall (ILW) of beryllium and tungsten. The influence of the ILW on plasma operation and performance has been substantial. Considerable progress has been made on optimising performance with the all-metal wall. Indeed, operation at the (normalised) ITER reference confinement and pressure has been re-established in JET albeit not yet at high current. In parallel with the physics development, extensive technical preparations are being made to operate JET with tritium. The state and scope of these preparations is reviewed, including the work being done on the safety case for DT operation and on upgrading machine infrastructure and diagnostics. A specific example of the latter is the planned calibration at

  17. Summary report on tokamak confinement experiments

    International Nuclear Information System (INIS)

    1982-03-01

    There are currently five major US tokamaks being operated and one being constructed under the auspices of the Division of Toroidal Confinement Systems. The currently operating tokamaks include: Alcator C at the Massachusetts Institute of Technology, Doublet III at the General Atomic Company, the Impurity Studies Experiment (ISX-B) at the Oak Ridge National Laboratory, and the Princeton Large Torus (PLT) and the Poloidal Divertor Experiment (PDX) at the Princeton Plasma Physics Laboratory. The Tokamak Fusion Test Reactor (TFTR) is under construction at Princeton and should be completed by December 1982. There is one major tokamak being funded by the Division of Applied Plasma Physics. The Texas Experimental Tokamak (TEXT) is being operated as a user facility by the University of Texas. The TEXT facility includes a complete set of standard diagnostics and a data acquisition system available to all users

  18. Evolution of the radial electric field in a JET H-mode plasma

    International Nuclear Information System (INIS)

    Andrew, Y.; Hawkes, N.C.; Biewer, T.; Crombe, K.; Keeling, D.; De la Luna, E.; Giroud, C.; Korotkov, A.; Meigs, A.; Murari, A.; Nunes, I.; Sartori, R.; Tala, T.; Andrew, Y.; Hawkes, N.C.; Keeling, D.; Giroud, C.; Korotkov, A.; Meigs, A.; Biewer, T.; Crombe, K.; De la Luna, E.; Murari, A.; Nunes, I.; Sartori, R.; Tala, T.

    2008-01-01

    Results from recent measurements of carbon impurity ion toroidal and poloidal rotation velocities, ion temperature, ion density and the resulting radial electric field (E r ) profiles are presented from an evolving Joint European Torus (JET) tokamak plasma over a range of energy and particle confinement regimes. Significant levels of edge plasma poloidal rotation velocity have been measured for the first time on JET, with maximum values of ±9 km/s. Such values of poloidal rotation provide an important contribution to the total edge plasma E r profiles. Large values of shear in the measured E r profiles are observed to arise as a consequence of the presence of the edge transport barrier (ETB) and do not appear to be necessary for their formation or destruction. These results have an important impact on potential mechanisms for transport barrier triggering and sustainment in present-day and future high-performance fusion plasmas. (authors)

  19. Ideal and resistive MHD stability of internal kink modes in circular and shaped tokamaks

    International Nuclear Information System (INIS)

    Bondeson, A.; Luetjens, H.; Vlad, G.

    1992-01-01

    Recent results for the MHD stability of internal kink modes in tokamaks are reviewed. In general, ideal stability is more restrictive than the conventionally cited limit β p p is the poloidal beta at the q = 1 surface). This holds, in particular, for shaped equilibria, where low shear in combination with elliptic shaping can drastically reduce the pressure limit. Also in resistive MHD, interchange effects are frequently destabilizing, and resistive stability at β p ≥0.05 is achieved, for circular section, only with a very restricted class of current profiles, and not at all for JET-shaped cross section. (author) 9 figs., 24 refs

  20. Power deposition for ion cyclotron heating in large tokamaks

    International Nuclear Information System (INIS)

    Hellsten, T.; Villard, L.

    1988-01-01

    The power deposition profiles during minority ion cyclotron heating are analysed in large tokamaks by using the global, toroidal wave code LION. For tokamaks with large aspect ratio and with circular cross-section, the wave is focused on the magnetic axis and can be absorbed there by cyclotron absorption when the cyclotron resonance passes through the magnetic axis. The power deposition profile is then essentially determined by the Doppler broadening of the ion cyclotron resonance. For equilibria either non-circular or with a small aspect ratio the power deposition profile depends also on the strength of the damping. In this case the power deposition profile can be expressed as a sum of two power deposition profiles. One is related to the power absorbed in a single pass, and its shape is similar to that obtained for large aspect ratio and circular cross-section. The other profile is obtained by calculating the power deposition in the limit of weak damping, in which case the wave electric field is almost constant along the cyclotron resonance layer. A heuristic formula for the power deposition is given. The formula includes a number of calibration curves and functions which has been calculated with the LION code for JET relevant equilibria. The formula enables calculation of the power deposition profile in a simple way when the launched wave spectrum and damping coefficients are known. (author). 7 refs, 11 figs

  1. The JET Alfven Eigenmode Local Manager for the real-time detection and tracking of a frequency-degenerate spectrum of MHD instabilities

    International Nuclear Information System (INIS)

    Testa, D.; Carfantan, H.; Fasoli, A.; Goodyear, A.; King, Q.; Blanchard, P.; Klein, A.; Lavanchy, P.; Panis, T.

    2011-01-01

    We present the real-time VME system used to detect and track MHD instabilities, and particularly Alfven Eigenmodes, on the JET tokamak [J. Wesson, Tokamaks, 3rd ed., Oxford Science Publication, Oxford, 2003, p. 617]. This system runs on a 1 kHz clock cycle, and allows performing a real-time, unsupervised and blind detection, decomposition and tracking of the individual components in a frequency-degenerate, multi-harmonic spectrum, using a small number of input data which are unevenly sampled in the spatial domain. This makes it possible to follow in real-time the detected modes as the plasma background evolves, and measure in real-time their frequency, damping rate, toroidal mode-number and relative amplitude. The successful implementation of this system opens a clear path towards developing real-time control tools for electro-magnetic instabilities in future fusion devices aimed at achieving a net energy gain, such as ITER [J. Wesson, Tokamaks, 3rd ed., Oxford Science Publication, Oxford, 2003, p. 711].

  2. Physics of the interaction between runaway electrons and the background plasma of the current quench in tokamak disruptions

    Science.gov (United States)

    Reux, Cedric

    2017-10-01

    Runaway electrons are created during disruptions of tokamak plasmas. They can be accelerated in the form of a multi-MA beam at energies up to several 10's of MeV. Prevention or suppression of runaway electrons during disruptions will be essential to ensure a reliable operation of future tokamaks such as ITER. Recent experiments showed that the suppression of an already accelerated beam with massive gas injection was unsuccessful at JET, conversely to smaller tokamaks. This was attributed to a dense, cold background plasma (up to several 1020 m-3 accompanying the runaway beam. The present contribution reports on the latest experimental results obtained at JET showing that some mitigation efficiency can be restored by changing the features of the background plasma. The density, temperature, position of the plasma and the energy of runaways were characterized using a combined analysis of interferometry, soft X-rays, bolometry, magnetics and hard X-rays. It showed that lower density background plasmas were obtained using smaller amounts of gas to trigger the disruption, leading to an improved penetration of the mitigation gas. Based on the observations, a physical model of the creation of the background plasma and its subsequent evolution is proposed. The plasma characteristics during later stages of the disruption are indeed dependent on the way it was initially created. The sustainment of the plasma during the runaway beam phase is then addressed by making a power balance between ohmic heating, power transfer from runaway electrons, radiation and atomic processes. Finally, a model of the interaction of the plasma with the mitigation gas is proposed to explain why massive gas injection of runaway beams works only in specific situations. This aims at pointing out which parameters bear the most importance if this mitigation scheme is to be used on larger devices like ITER. Acknowledgement: This work has been carried out within the framework of the EUROfusion Consortium

  3. Tritium Removal from JET and TFTR Tiles by a Scanning Laser

    International Nuclear Information System (INIS)

    Skinner, C.H.; Bekris, N.; Coad, J.P.; Gentile, C.A.; Glugla, M.

    2002-01-01

    Fast and efficient tritium removal is needed for future D-T machines with carbon plasma-facing components. A novel method for tritium release has been demonstrated on co-deposited layers on tiles retrieved from the Tokamak Fusion Test Reactor (TFTR) and from the Joint European Torus (JET). A scanning continuous wave neodymium laser beam was focused to =100 W/mm2 and scanned at high speed over the co-deposits, heating them to temperatures =2000 C for about 10 ms in either air or argon atmospheres. Fiber optic coupling between the laser and scanner was implemented. Up to 87% of the co-deposited tritium was thermally desorbed from the JET and TFTR samples. This technique appears to be a promising in-situ method for tritium removal in a next-step D-T device as it avoids oxidation, the associated de-conditioning of the plasma-facing surfaces, and the expense of processing large quantities of tritium oxide

  4. Research using small tokamaks

    International Nuclear Information System (INIS)

    1991-01-01

    The technical reports contained in this collection of papers on research using small tokamaks fall into four main categories, i.e., (i) experimental work (heating, stability, plasma radial profiles, fluctuations and transport, confinement, ultra-low-q tokamaks, wall physics, a.o.), (ii) diagnostics (beam probes, laser scattering, X-ray tomography, laser interferometry, electron-cyclotron absorption and emission systems), (iii) theory (strong turbulence, effects of heating on stability, plasma beta limits, wave absorption, macrostability, low-q tokamak configurations and bootstrap currents, turbulent heating, stability of vortex flows, nonlinear islands growth, plasma-drift-induced anomalous transport, ergodic divertor design, a.o.), and (iv) new technical facilities (varistors applied to establish constant current and loop voltage in HT-6M), lower-hybrid-current-drive systems for HT-6B and HT-6M, radio-frequency systems for HT-6M ICR heating experimentation, and applications of fiber optics for visible and vacuum ultraviolet radiation detection as applied to tokamaks and reversed-field pinches. A total number of 51 papers are included in the collection. Refs, figs and tabs

  5. A theory of self-organized zonal flow with fine radial structure in tokamak

    Science.gov (United States)

    Zhang, Y. Z.; Liu, Z. Y.; Xie, T.; Mahajan, S. M.; Liu, J.

    2017-12-01

    The (low frequency) zonal flow-ion temperature gradient (ITG) wave system, constructed on Braginskii's fluid model in tokamak, is shown to be a reaction-diffusion-advection system; it is derived by making use of a multiple spatiotemporal scale technique and two-dimensional (2D) ballooning theory. For real regular group velocities of ITG waves, two distinct temporal processes, sharing a very similar meso-scale radial structure, are identified in the nonlinear self-organized stage. The stationary and quasi-stationary structures reflect a particular feature of the poloidal group velocity. The equation set posed to be an initial value problem is numerically solved for JET low mode parameters; the results are presented in several figures and two movies that show the spatiotemporal evolutions as well as the spectrum analysis—frequency-wave number spectrum, auto power spectrum, and Lissajous diagram. This approach reveals that the zonal flow in tokamak is a local traveling wave. For the quasi-stationary process, the cycle of ITG wave energy is composed of two consecutive phases in distinct spatiotemporal structures: a pair of Cavitons growing and breathing slowly without long range propagation, followed by a sudden decay into many Instantons that carry negative wave energy rapidly into infinity. A spotlight onto the motion of Instantons for a given radial position reproduces a Blob-Hole temporal structure; the occurrence as well as the rapid decay of Caviton into Instantons is triggered by zero-crossing of radial group velocity. A sample of the radial profile of zonal flow contributed from 31 nonlinearly coupled rational surfaces near plasma edge is found to be very similar to that observed in the JET Ohmic phase [J. C. Hillesheim et al., Phys. Rev. Lett. 116, 165002 (2016)]. The theory predicts an interior asymmetric dipole structure associated with the zonal flow that is driven by the gradients of ITG turbulence intensity.

  6. Accelerator technology in tokamaks

    International Nuclear Information System (INIS)

    Kustom, R.L.

    1977-01-01

    This article presents the similarities in the technology required for high energy accelerators and tokamak fusion devices. The tokamak devices and R and D programs described in the text represent only a fraction of the total fusion program. The technological barriers to producing successful, economical tokamak fusion power plants are as many as the plasma physics problems to be overcome. With the present emphasis on energy problems in this country and elsewhere, it is very likely that fusion technology related R and D programs will vigorously continue; and since high energy accelerator technology has so much in common with fusion technology, more scientists from the accelerator community are likely to be attracted to fusion problems

  7. Jet observables without jet algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Bertolini, Daniele; Chan, Tucker; Thaler, Jesse [Center for Theoretical Physics, Massachusetts Institute of Technology,Cambridge, MA 02139 (United States)

    2014-04-02

    We introduce a new class of event shapes to characterize the jet-like structure of an event. Like traditional event shapes, our observables are infrared/collinear safe and involve a sum over all hadrons in an event, but like a jet clustering algorithm, they incorporate a jet radius parameter and a transverse momentum cut. Three of the ubiquitous jet-based observables — jet multiplicity, summed scalar transverse momentum, and missing transverse momentum — have event shape counterparts that are closely correlated with their jet-based cousins. Due to their “local” computational structure, these jet-like event shapes could potentially be used for trigger-level event selection at the LHC. Intriguingly, the jet multiplicity event shape typically takes on non-integer values, highlighting the inherent ambiguity in defining jets. By inverting jet multiplicity, we show how to characterize the transverse momentum of the n-th hardest jet without actually finding the constituents of that jet. Since many physics applications do require knowledge about the jet constituents, we also build a hybrid event shape that incorporates (local) jet clustering information. As a straightforward application of our general technique, we derive an event-shape version of jet trimming, allowing event-wide jet grooming without explicit jet identification. Finally, we briefly mention possible applications of our method for jet substructure studies.

  8. Texas Experimental Tokamak

    International Nuclear Information System (INIS)

    Wootton, A.J.

    1993-04-01

    This progress report covers the period from November 1, 1990 to April 30, 1993. During that period, TEXT was operated as a circular tokamak with a material limiter. It was devoted to the study of basic plasma physics, in particular to study of fluctuations, turbulence, and transport. The purpose is to operate and maintain TEXT Upgrade as a complete facility for applied tokamak physics, specifically to conduct a research program under the following main headings: (1) to elucidate the mechanisms of working gas, impurity, and thermal transport in tokamaks, in particular to understand the role of turbulence; (2) to study physics of the edge plasma, in particular the turbulence; (3) to study the physics or resonant magnetic fields (ergodic magnetic divertors, intra island pumping); and (4) to study the physics of electron cyclotron heating (ECRH). Results of studies in each of these areas are reported

  9. START: the creation of a spherical tokamak

    International Nuclear Information System (INIS)

    Sykes, Alan

    1992-01-01

    The START (Small Tight Aspect Ratio Tokamak) plasma fusion experiment is now operational at AEA Fusion's Culham Laboratory. It is the world's first experiment to explore an extreme limit of the tokamak - the Spherical Tokamak - which theoretical studies predict may have substantial advantages in the search for economic fusion power. The Head of the START project, describes the concept, some of the initial experimental results and the possibility of developing a spherical tokamak power reactor. (author)

  10. Distribution of erosion and deposition on the JET belt limiters

    International Nuclear Information System (INIS)

    McCracken, G.M.; Goodall, D.H.J.; Behrisch, R.; Roth, J.; Coad, J.P.; Harbour, P.; Kock, L. de; Pick, M.A.; Stangeby, P.C.

    1989-01-01

    The distribution of erosion and deposition of limiter material is of importance both for extrapolating to the next generation of fusion machines and for understanding impurity transport in the boundary layers of present day tokamaks. Erosion patterns have previously been reported for the JET discrete graphite limiters used up to 1986. We have now made measurements on the belt limiters used in 1987-88. These measurements show that although the pattern of net erosion is qualitatively similar to the earlier results the new maximum erosion (∼40μm) is reduced by about a factor 5, consistent with the larger limiter surface area. (author) 7 refs., 2 figs

  11. Calibration of neutron yield activation measurements at JET using MCNP and furnace neutron transport codes

    International Nuclear Information System (INIS)

    Pillon, M.; Martone, M.; Verschuur, K.A.; Jarvis, O.N.; Kaellne, J.

    1989-01-01

    Neutron transport calculations have been performed using fluence ray tracing (FURNACE code) and Monte Carlo particle trajectory sampling methods (MCNP code) in order to determine the neutron fluence and energy distributions at different locations in the JET tokamak. These calculations were used to calibrate the activation measurements used in the determination of the absolute fusion neutron yields from the JET plasma. We present here the neutron activation response coefficients calculated for three different materials. Comparison of the MCNP and FURNACE results helps identify the sources of error in these neutron transport calculations. The accuracy of these calculations was tested by comparing the total 2.5 MeV neutron yields derived from the activation measurements with those obtained with calibrated fission chambers; agreement at the ±15% level was demonstrate. (orig.)

  12. Ion target impact energy during Type I edge localized modes in JET ITER-like Wall

    Czech Academy of Sciences Publication Activity Database

    Guillemaut, C.; Jardin, A.; Horáček, Jan; Autrique, A.; Arnoux, G.; Boom, J.; Brezinsek, S.; Coenen, J.W.; De La Luna, E.; Devaux, S.; Eich, T.; Giroud, C.; Harting, D.; Kirschner, A.; Lipschutz, B.; Matthews, G.F.; Moulton, D.; O’Mullane, M.; Stamp, M.

    2015-01-01

    Roč. 57, č. 8 (2015), č. článku 085006. ISSN 0741-3335 R&D Projects: GA MŠk LG14002 EU Projects: European Commission(XE) 633053 Institutional support: RVO:61389021 Keywords : magnetic confinement fusion * edge localized modes * JET ITER-like wall * plasma * tokamak Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 2.404, year: 2015 http://dx.doi.org/10.1088/0741-3335/57/8/085006

  13. Modelling dust transport in tokamaks

    International Nuclear Information System (INIS)

    Martin, J.D.; Martin, J.D.; Bacharis, M.; Coppins, M.; Counsell, G.F.; Allen, J.E.; Counsell, G.F.

    2008-01-01

    The DTOKS code, which models dust transport through tokamak plasmas, is described. The floating potential and charge of a dust grain in a plasma and the fluxes of energy to and from it are calculated. From this model, the temperature of the dust grain can be estimated. A plasma background is supplied by a standard tokamak edge modelling code (B2SOLPS5.0), and dust transport through MAST (the Mega-Amp Spherical Tokamak) and ITER plasmas is presented. We conclude that micron-radius tungsten dust can reach the separatrix in ITER. (authors)

  14. Compact tokamak reactors

    International Nuclear Information System (INIS)

    Wootton, A.J.; Wiley, J.C.; Edmonds, P.H.; Ross, D.W.

    1997-01-01

    The possible use of tokamaks for thermonuclear power plants is discussed, in particular tokamaks with low aspect ratio and copper toroidal field coils. Three approaches are presented. First, the existing literature is reviewed and summarized. Second, using simple analytic estimates, the size of the smallest tokamak to produce an ignited plasma is derived. This steady state energy balance analysis is then extended to determine the smallest tokamaks power plant, by including the power required to drive the toroidal field and by considering two extremes of plasma current drive efficiency. Third, the analytic results are augmented by a numerical calculation that permits arbitrary plasma current drive efficiency and different confinement scaling relationships. Throughout, the importance of various restrictions is emphasized, in particular plasma current drive efficiency, plasma confinement, plasma safety factor, plasma elongation, plasma beta, neutron wall loading, blanket availability and recirculation of electric power. The latest published reactor studies show little advantage in using low aspect ratios to obtain a more compact device (and a low cost of electricity) unless either remarkably high efficiency plasma current drive and low safety factor are combined, or unless confinement (the H factor), the permissible elongation and the permissible neutron wall loading increase as the aspect ratio is reduced. These results are reproduced with the analytic model. (author). 22 refs, 3 figs

  15. Searching for jets using a transverse-energy trigger

    International Nuclear Information System (INIS)

    Singer, R.; Fields, T.; Selove, W.

    1982-01-01

    We have studied the question of whether prominent jet structure would be expected in hadron-hadron collision events which are selected on the basis of having a large amount of transverse energy carried by the final-state hadrons. Using a computer simulation based on the Field-Feynman parton scattering model, we find that such a transverse-energy selection does not yield events predominantly having clear jet structure; this finding is in agreement with data from experiment NA5 at CERN. The basic reason for this effect is that high-multiplicity fragmentation of the beam and target spectator partons will contribute a substantial fraction of the transverse energy while also diluting the jet structure

  16. Magnetic confinement experiment -- 1: Tokamaks

    International Nuclear Information System (INIS)

    Goldston, R.J.

    1994-01-01

    This report reviews presentations made at the 15th IAEA Conference on Plasma Physics and Controlled Nuclear Fusion on experimental tokamak physics, particularly on advances in core plasma physics, divertor and edge physics, heating and current drive, and tokamak concept optimization

  17. Microwave Tokamak Experiment: Overview and status

    International Nuclear Information System (INIS)

    1990-05-01

    The Microwave Tokamak Experiment, now under construction at the Laboratory, will use microwave heating from a free-electron laser. The intense microwave pulses will be injected into the tokamak to realize several goals, including a demonstration of the effects of localized heat deposition within magnetically confined plasma, a better understanding of energy confinement in tokamaks, and use of the new free-electron laser technology for plasma heating. 3 figs., 3 tabs

  18. Advanced statistics for tokamak transport colinearity and tokamak to tokamak variation

    International Nuclear Information System (INIS)

    Riedel, K.S.

    1989-01-01

    This paper is an expository introduction to advanced statistics and scaling laws and their application to tokamak devices. Topics of discussion are as follows: implicit assumptions in the standard analysis; advanced regression techniques; specialized tools in statistics and their applications in fusion physics; and improved datasets for transport studies

  19. Magnetic ''islandography'' in tokamaks

    International Nuclear Information System (INIS)

    Callen, J.D.; Waddell, B.V.; Hicks, H.R.

    1978-09-01

    Tearing modes are shown to be responsible for most of the experimentally observed macroscopic behavior of tokamak discharges. The effects of these collective magnetic perturbations on magnetic topology and plasma transport in tokamaks are shown to provide plausible explanations for: internal disruptions (m/n = 1); Mirnov oscillations (m/n = 2,3...); and major disruptions (coupling of 2/1-3/2 modes). The nonlinear evolution of the tearing modes is followed with fully three-dimensional computer codes. The effects on plasma confinement of the magnetic islands or stochastic field lines induced by the macroscopic tearing modes are discussed and compared with experiment. Finally, microscopic magnetic perturbations are shown to provide a natural model for the microscopic anomalous transport processes in tokamaks

  20. Probability distribution functions for ELM bursts in a series of JET tokamak discharges

    International Nuclear Information System (INIS)

    Greenhough, J; Chapman, S C; Dendy, R O; Ward, D J

    2003-01-01

    A novel statistical treatment of the full raw edge localized mode (ELM) signal from a series of previously studied JET plasmas is tested. The approach involves constructing probability distribution functions (PDFs) for ELM amplitudes and time separations, and quantifying the fit between the measured PDFs and model distributions (Gaussian, inverse exponential) and Poisson processes. Uncertainties inherent in the discreteness of the raw signal require the application of statistically rigorous techniques to distinguish ELM data points from background, and to extrapolate peak amplitudes. The accuracy of PDF construction is further constrained by the relatively small number of ELM bursts (several hundred) in each sample. In consequence the statistical technique is found to be difficult to apply to low frequency (typically Type I) ELMs, so the focus is narrowed to four JET plasmas with high frequency (typically Type III) ELMs. The results suggest that there may be several fundamentally different kinds of Type III ELMing process at work. It is concluded that this novel statistical treatment can be made to work, may have wider applications to ELM data, and has immediate practical value as an additional quantitative discriminant between classes of ELMing behaviour

  1. Electromagnetic simulations of JET ICRF ITER-like antenna with TOPICA and SSWICH asymptotic codes

    Directory of Open Access Journals (Sweden)

    Křivská Alena

    2017-01-01

    Full Text Available Multi-megawatt Ion Cyclotron Range of Frequencies (ICRF heating is routinely used in the JET tokamak. To increase the ICRF heating power available from the A2 antennas, the ICRF ITER-Like Antenna (ILA was reinstalled for the 2015 JET ITER-like wall experimental campaign. The application of high levels of ICRF power typically results in increased plasma wall interaction which leads to the observation of enhanced influx of metallic impurities in the plasma edge. It is assumed that the impurity production is mainly driven by the parallel component of the Radio-Frequency (RF antenna electric near-field, E// (parallel to the confinement magnetic field of the tokamak, that is rectified in a thin boundary layer (RF sheath. Torino Polytechnic Ion Cyclotron Antenna (TOPICA code was used to compute E// field maps in front of the ILA and between its poloidal limiters in the presence of plasma using measured density profiles and various antenna feedings. E// field maps calculated between the poloidal limiters were used to estimate the poloidal distribution of RF-sheath Direct Current (DC potential in this private region of the ILA and make relative comparison of various antenna electrical settings. For this purpose we used the asymptotic version of the Self-consistent Sheaths and Waves for Ion Cyclotron Heating Slow-Wave (SSWICH-SW code. These estimations can help to study the formation of RF sheaths around the antenna and even at distant locations (∼3m away.

  2. Very forward jet, Mueller Navelet jets and jet gap jet measurements in CMS

    CERN Document Server

    Cerci, Salim

    2018-01-01

    The measurements of very forward jet, Mueller-Navelet jets and jet-gap-jet events are presented for different collision energies. The analyses are based on data collected with the CMS detector at the LHC. Jets are defined through the anti-$k_\\mathrm{t}$ clustering algorithm for different cone sizes. Jet production studies provide stringent tests of quantum chromodynamics (QCD) and contribute to tune Monte Carlo (MC) simulations and phenomenological models. The measurements are compared to predictions from various Monte Carlo event generators.

  3. Disruption mitigation with high-pressure helium gas injection on EAST tokamak

    Science.gov (United States)

    Chen, D. L.; Shen, B.; Granetz, R. S.; Qian, J. P.; Zhuang, H. D.; Zeng, L.; Duan, Y.; Shi, T.; Wang, H.; Sun, Y.; Xiao, B. J.

    2018-03-01

    High pressure noble gas injection is a promising technique to mitigate the effect of disruptions in tokamaks. In this paper, results of mitigation experiments with low-Z massive gas injection (helium) on the EAST tokamak are reported. A fast valve has been developed and successfully implemented on EAST, with valve response time  ⩽150 μs, capable of injecting up to 7 × 1022 particles, corresponding to 300 times the plasma inventory. Different amounts of helium gas were injected into stable plasmas in the preliminary experiments. It is seen that a small amount of helium gas (N_He≃ N_plasma ) can not terminate a discharge, but can trigger MHD activity. Injection of 40 times the plasma inventory impurity (N_He≃ 40× N_plasma ) can effectively radiate away part of the thermal energy and make the electron density increase rapidly. The mitigation result is that the current quench time and vertical displacement can both be reduced significantly, without resulting in significantly higher loop voltage. This also reduces the risk of runaway electron generation. As the amount of injected impurity gas increases, the gas penetration time decreases slowly and asymptotes to (˜7 ms). In addition, the impurity gas jet has also been injected into VDEs, which are more challenging to mitigate that stable plasmas.

  4. Remote handling installation of diagnostics in the JET Tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Allan, P., E-mail: Peter.Allan@ccfe.ac.uk [JET-EFDA, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Loving, A.B. [JET-EFDA, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Omran, H. [JET-EFDA, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Oxford Technologies Ltd, 7 Nuffield Way, Abingdon OX14 1RJ (United Kingdom); Collins, S.; Thomas, J. [JET-EFDA, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Parsloe, A.; Merrigan, I. [JET-EFDA, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); British Nuclear Services, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Hassall, I. [JET-EFDA, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Oxford Technologies Ltd, 7 Nuffield Way, Abingdon OX14 1RJ (United Kingdom)

    2011-10-15

    The requirement for an upgrade of the diagnostics for the JET ITER Like Wall (ILW) while maintaining personnel exposure to contamination as low as reasonably practicable or ALARP, has necessitated the development of a bespoke set of diagnostic components. These components, by virtue of their design and location, require a versatile yet comprehensive suite of remote handling tools to undertake their in-vessel installation. The installation of the various diagnostic components is covered in multiple tasks. Each task requires careful assessment and design of tools that can successfully interface with the components and comply with the handling and installation requirements. With remote maintenance a requirement, the looms/conduits were designed to be modular with connections which are electrically connected when the module is fitted or conversely disconnected when removed. The shape of each complex and often bulky component is verified during the design phase, to ensure that it can be delivered and installed to its specified location in the torus. This is done by matching the kinematic capabilities of the remote handling system and the path of the component through the torus by using a state of the art virtual reality system.

  5. Current drive by spheromak injection into a tokamak

    International Nuclear Information System (INIS)

    Brown, M.R.; Bellan, P.M.

    1990-01-01

    The authors report the first observation of current drive by spheromak injection into a tokamak due to the process of helicity injection. Current drive is observed in Caltech's ENCORE tokamak (30% increase, ΔI > 1 kA) only when both the tokamak and injected spheromak have the same sign of helicity (where helicity is defined as positive if current flows parallel to magnetic field lines and negative if anti-parallel). The initial increase (decrease) in current is accompanied by a sharp decrease (increase) in loop voltage and the increase in tokamak helicity is consistent with the helicity content of the injected spheromak. In addition, the injection of the spheromak raises the tokamak central density by a factor of six. The introduction of cold spheromak plasma causes sudden cooling of the tokamak discharge from 12 eV to 4 eV which results in a gradual decline in tokamak plasma current by a factor of three. In a second experiment, the authors inject spheromaks into the magnetized toroidal vacuum vessel (with no tokamak plasma). An m = 1 magnetic structure forms in the vessel after the spheromak undergoes a double tilt; once in the cylindrical entrance between gun and tokamak, then again in the tokamak vessel. A horizontal shift of the spheromak equilibrium is observed in the direction opposite that of the static toroidal field. In the absence of net toroidal flux, the structure develops a helical pitch as predicted by theory. Experiments with a number of refractory metal coatings have shown that tungsten and chrome coatings provide some improvement in spheromak parameters. They have also designed and will soon construct a larger, higher current spheromak gun with a new accelerator section for injection experiments on the Phaedrus-T tokamak

  6. Tritium Removal from JET and TFTR Tiles by a Scanning Laser; TOPICAL

    International Nuclear Information System (INIS)

    C.H. Skinner; N. Bekris; J.P. Coad; C.A. Gentile; M. Glugla

    2002-01-01

    Fast and efficient tritium removal is needed for future D-T machines with carbon plasma-facing components. A novel method for tritium release has been demonstrated on co-deposited layers on tiles retrieved from the Tokamak Fusion Test Reactor (TFTR) and from the Joint European Torus (JET). A scanning continuous wave neodymium laser beam was focused to=100 W/mm2 and scanned at high speed over the co-deposits, heating them to temperatures=2000 C for about 10 ms in either air or argon atmospheres. Fiber optic coupling between the laser and scanner was implemented. Up to 87% of the co-deposited tritium was thermally desorbed from the JET and TFTR samples. This technique appears to be a promising in-situ method for tritium removal in a next-step D-T device as it avoids oxidation, the associated de-conditioning of the plasma-facing surfaces, and the expense of processing large quantities of tritium oxide

  7. A need for non-tokamak approaches to magnetic fusion energy

    International Nuclear Information System (INIS)

    Bathke, C.G.; Krakowski, R.A.; Miller, R.L.

    1992-01-01

    Focusing exclusively on conventional tokamak physics in the quest for commercial fusion power is premature, and the options for both advanced-tokamak and non-tokamak concepts need continued investigation. The basis for this claim is developed, and promising advanced-tokamak and non-tokamak options are suggested

  8. Submillimeter wave propagation in tokamak plasmas

    International Nuclear Information System (INIS)

    Ma, C.H.; Hutchinson, D.P.; Staats, P.A.; Vander Sluis, K.L.; Mansfield, D.K.; Park, H.; Johnson, L.C.

    1985-01-01

    The propagation of submillimeter-waves (smm) in tokamak plasmas has been investigated both theoretically and experimentally to ensure successful measurements of electron density and plasma current distributions in tokamak devices. Theoretical analyses have been carried out to study the polarization of the smm waves in TFTR and ISX-B tokamaks. A multichord smm wave interferometer/polarimeter system has been employed to simultaneously measure the line electron density and poloidal field-induced Faraday rotation in the ISX-B tokamak. The experimental study on TFTR is under way. Computer codes have been developed and have been used to study the wave propagation and to reconstruct the distributions of plasma current and density from the measured data. The results are compared with other measurements

  9. Submillimeter wave propagation in tokamak plasmas

    International Nuclear Information System (INIS)

    Ma, C.H.; Hutchinson, D.P.; Staats, P.A.; Vander Sluis, K.L.; Mansfield, D.K.; Park, H.; Johnson, L.C.

    1986-01-01

    Propagation of submillimeter waves (smm) in tokamak plasma was investigated both theoretically and experimentally to ensure successful measurements of electron density and plasma current distributions in tokamak devices. Theoretical analyses were carried out to study the polarization of the smm waves in TFTR and ISX-B tokamaks. A multichord smm wave interferometer/polarimeter system was employed to simultaneously measure the line electron density and poloidal field-induced Faraday rotation in the ISX-B tokamak. The experimental study on TFTR is under way. Computer codes were developed and have been used to study the wave propagation and to reconstruct the distributions of plasma current and density from the measured data. The results are compared with other measurements. 5 references, 2 figures

  10. The role of the spherical tokamak in clarifying tokamak physics

    International Nuclear Information System (INIS)

    Morris, A.W.; Akers, R.J.; Connor, J.W.; Counsell, G.F.; Gryaznevich, M.P.; Hender, T.C.; Maddison, G.P.; Martin, T.J.; McClements, K.G.; Roach, C.M.; Robinson, D.C.; Sykes, A.; Valovic, M.; Wilson, H.R.; Fonck, R.J.; Gusev, V.; Kaye, S.M.; Majeski, R.; Peng, Y.-K.M.; Medvedev, S.; Sharapov, S.; Walsh, M.J.

    1999-01-01

    The spherical tokamak (ST) provides a unique environment in which to perform complementary and exacting tests of the tokamak physics required for a burning plasma experiment of any aspect ratio, while also having the potential for long-term fusion applications in its own right. New experiments are coming on-line in the UK (MAST), USA (NSTX, Pegasus), Russia (Globus-M), Brazil (ETE) and elsewhere, and the status of these devices will be reported, along with newly-analysed data from START. Those physics issues where the ST provides an opportunity to remove degeneracy in the databases or clarify one's understanding will be emphasized. (author)

  11. Identification of krypton Kr XVIII to Kr XXIX spectra excited in TFR Tokamak plasmas

    International Nuclear Information System (INIS)

    Wyart, J.F.

    1985-02-01

    The emission spectrum of krypton (injected into TFR tokamak plasmas) has been recorded photographically in the 15-300 A spectral range by means of a 2m grazing incidence spectrograph. Preliminary identification work, based on isoelectronic regularities from known spectra of other ions and ionization equilibrium calculations, has allowed 48 lines (belonging to the O I, F I, Na I, Mg I, Al I, Ar I and K I sequences) to be identified

  12. Experimental investigation of heat transport and divertor loads of fusion plasmas in all metal ASDEX upgrade and JET

    International Nuclear Information System (INIS)

    Sieglin, Bernhard A.

    2014-01-01

    This work presents divertor heat load studies conducted at two of the largest tokamaks currently in operation, ASDEX Upgrade and the Joint European Torus (JET). A commonly agreed empirical scaling for the power fall-off length in H-mode obtained in carbon devices is validated in JET with the ILW. Bohm and Gyro-Bohm like models are identified as possible candidates describing the divertor broadening. Quantities for the assessment of the thermal load induced by transient heat loads are defined. JET with the ILW exhibits an on average longer ELM duration as compared to the carbon wall. For identical pedestal conditions the ELM durations in both cases are found to be the same within error bars. The energy fluency is found to depend mainly on the pedestal pressure with a weak dependence on the relative loss in stored energy. This is noteworthy since the current extrapolation to ITER assumes a linear dependence on the relative ELM size.

  13. Advanced tokamak burning plasma experiment

    International Nuclear Information System (INIS)

    Porkolab, M.; Bonoli, P.T.; Ramos, J.; Schultz, J.; Nevins, W.N.

    2001-01-01

    A new reduced size ITER-RC superconducting tokamak concept is proposed with the goals of studying burn physics either in an inductively driven standard tokamak (ST) mode of operation, or in a quasi-steady state advanced tokamak (AT) mode sustained by non-inductive means. This is achieved by reducing the radiation shield thickness protecting the superconducting magnet by 0.34 m relative to ITER and limiting the burn mode of operation to pulse lengths as allowed by the TF coil warming up to the current sharing temperature. High gain (Q≅10) burn physics studies in a reversed shear equilibrium, sustained by RF and NB current drive techniques, may be obtained. (author)

  14. Computational studies of tokamak plasmas

    International Nuclear Information System (INIS)

    Takizuka, Tomonori; Tsunematsu, Toshihide; Tokuda, Shinji

    1981-02-01

    Computational studies of tokamak plasmas are extensively advanced. Many computational codes have been developed by using several kinds of models, i.e., the finite element formulation of MHD equations, the time dependent multidimensional fluid model, and the particle model with the Monte-Carlo method. These codes are applied to the analyses of the equilibrium of an axisymmetric toroidal plasma (SELENE), the time evolution of the high-beta tokamak plasma (APOLLO), the low-n MHD stability (ERATO-J) and high-n ballooning mode stability (BOREAS) in the INTOR tokamak, the nonlinear MHD stability, such as the positional instability (AEOLUS-P), resistive internal mode (AEOLUS-I) etc., and the divertor functions. (author)

  15. Combined confinement system applied to tokamaks

    International Nuclear Information System (INIS)

    Ohkawa, Tihiro

    1986-01-01

    From particle orbit point of view, a tokamak is a combined confinement configuration where a closed toroidal volume is surrounded by an open confinement system like a magnetic mirror. By eliminating a cold halo plasma, the energy loss from the plasma becomes convective. The H-mode in diverted tokamaks is an example. Because of the favorable scaling of the energy confinement time with temperature, the performance of the tokamak may be significantly improved by taking advantage of this effect. (author)

  16. Poloidal electric field and variation of radial transport during ICRF heating in the JET scrape-off layer

    International Nuclear Information System (INIS)

    Clement, S.; Tagle, J.A.; Bures, M.; Vince, J.; Kock, L. de; Stangeby, P.C.

    1989-01-01

    The highly anomalous perpendicular transport in the plasma edge of a tokamak is generally attributed to plasma turbulence, primarily to density and electrostatic potential fluctuations. The edge transport could be modified by changing the geometry of objects in contact with the plasma (limiters, radio frequency antennae ...) and during additional heating experiments. Poloidal asymmetries in the scrape-off layer (SOL) in tokamaks using poloidal limiters (eg. ALCATOR-C) have been recently reported, indicating a poloidal asymmetry in cross-field transport. A poloidal ring limiter obstructs communications between different flux tubes in the SOL, thus permitting poloidal asymmetries in n e and T e to develop if D perpendicular is θ-dependent. When JET was operated with discrete limiters, equivalent to a single toroidal limiter at the outside mid-plane, little poloidal variation in the SOL plasma properties was observed. Currently JET is operated with two complete toroidal belt limiters located approximately one meter above and below the outside mid-plane. This configuration breaks the SOL into two regions: the low field side SOL (LFS), between the limiters, and the rest of the SOL on the high field side (HFS). Differences on the scrape-off lengths in the two SOLs are reported here, indicating that cross-field transport is faster on the LFS-SOL, in agreement with observations made on ASDEX and T-10. (author) 8 refs., 6 figs

  17. The density limit in Tokamaks

    International Nuclear Information System (INIS)

    Alladio, F.

    1985-01-01

    A short summary of the present status of experimental observations, theoretical ideas and understanding of the density limit in tokamaks is presented. It is the result of the discussion that was held on this topic at the 4th European Tokamak Workshop in Copenhagen (December 4th to 6th, 1985). 610 refs

  18. Overview of erosion–deposition diagnostic tools for the ITER-Like Wall in the JET tokamak

    International Nuclear Information System (INIS)

    Rubel, M.; Coad, J.P.; Widdowson, A.; Matthews, G.F.; Esser, H.G.; Hirai, T.; Likonen, J.; Linke, J.; Lungu, C.P.; Mayer, M.; Pedrick, L.; Ruset, C.

    2013-01-01

    This paper presents scientific and technical issues related to the development of erosion–deposition diagnostic tools for JET operated with the ITER-Like Wall: beryllium and tungsten marker tiles and several types of wall probes installed in the main chamber and in the divertor. Markers tiles are the standard limiter and divertor components additionally coated first with a thin sandwich of Ni–Be and Mo–W for, beryllium and tungsten markers, respectively. Both types of markers are embedded in regular arrays of limiter and divertor tiles. Coated W–Be probes are also inserted in the Be-covered Inconel cladding tiles on the central column. Other types of erosion–deposition diagnostic tools are: rotating collectors, deposition traps, louver clips, quartz microbalance and mirrors for the First Mirror Test at JET for ITER. The specific role of these tools is discussed in detail

  19. Development of Operation Scenario for Spherical Tokamak at SNU

    International Nuclear Information System (INIS)

    Sung, C. K.; Park, Y. S.; Lee, H. Y.; Kang, J.; Hwang, Y. S.

    2009-01-01

    Several concepts for nuclear fusion plant exist. In these concepts, tokamak is the most promising one to realize nuclear fusion plant. Though tokamak has leading concept, and this has world record in fusion heating power, tokamak has the critical drawback: low heating efficiency. That is the reason why we need another alternative concept which compensates tokamak's disadvantage. Spherical Torus(ST) is one of these kinds of concepts. ST is a kind of tokamak which has low aspect ratio. This feature gives ST advantages compared to conventional tokamak: high efficiency, compactness, low cost. However, ST lacks central region for solenoid that is needed to start-up and sustain. Since it is the most efficient that initializing and sustaining by using solenoid, this is ST's intrinsic limitation. To overcome this, a new device which can start-up and sustain ST plasmas by means of continuous tokamak plasma injection has been designed

  20. Generating Long Scale-Length Plasma Jets Embedded in a Uniform, Multi-Tesla Magnetic-Field

    Science.gov (United States)

    Manuel, Mario; Kuranz, Carolyn; Rasmus, Alex; Klein, Sallee; Fein, Jeff; Belancourt, Patrick; Drake, R. P.; Pollock, Brad; Hazi, Andrew; Park, Jaebum; Williams, Jackson; Chen, Hui

    2013-10-01

    Collimated plasma jets emerge in many classes of astrophysical objects and are of great interest to explore in the laboratory. In many cases, these astrophysical jets exist within a background magnetic field where the magnetic pressure approaches the plasma pressure. Recent experiments performed at the Jupiter Laser Facility utilized a custom-designed solenoid to generate the multi-tesla fields necessary to achieve proper magnetization of the plasma. Time-gated interferometry, Schlieren imaging, and proton radiography were used to characterize jet evolution and collimation under varying degrees of magnetization. Experimental results will be presented and discussed. This work is funded by the NNSA-DS and SC-OFES Joint Program in High-Energy-Density Laboratory Plasmas, grant number DE-NA0001840, by the National Laser User Facility Program, grant number DE-NA0000850, by the Predictive Sciences Academic Alliances Program in NNSA-ASC, grant number DEFC52-08NA28616, and by NASA through Einstein Postdoctoral Fellowship grant number PF3-140111 awarded by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory for NASA under contract NAS8-03060.

  1. Economic considerations of commercial tokamak options

    International Nuclear Information System (INIS)

    Dabiri, A.E.

    1986-05-01

    Systems studies have been performed to assess commercial tokamak options. Superconducting, as well as normal, magnet coils in either first or second stability regimes have been considered. A spherical torus (ST), as well as an elongated tokamak (ET), is included in the study. The cost of electricity (COE) is selected as the figure of merit, and beta and first-wall neutron wall loads are selected to represent the physics and technology characteristics of various options. The results indicate that an economical optimum for tokamaks is predicted to require a beta of around 10%, as predicted to be achieved in the second stability regime, and a wall load of about 5 MW/m 2 , which is assumed to be optimum technologically. This tokamak is expected to be competitive with fission plants if efficient, noninductive current drive is developed. However, if this regime cannot be attained, all other tokamaks operating in the first stability regime, including spherical torus and elongated tokamak and assuming a limiting wall load of 5 MW/m 2 , will compete with one another with a COE of about 50 mill/kWh. This 40% higher than the COE for the optimum reactor in the second stability regime with fast-wave current drive. The above conclusions pertain to a 1200-MW(e) net electric power plant. A comparison was also made between ST, ET, and superconducting magnets in the second stability regime with fast-wave current drive at 600 MW(e)

  2. Large aspect ratio tokamak study

    International Nuclear Information System (INIS)

    Reid, R.L.; Holmes, J.A.; Houlberg, W.A.; Peng, Y.K.M.; Strickler, D.J.; Brown, T.G.; Sardella, C.; Wiseman, G.W.

    1979-01-01

    The Large Aspect Ratio Tokamak Study (LARTS) investigated the potential for producing a viable long burn tokamak reactor through enhanced volt-second capability of the ohmic heating transformer by employing high aspect ratio designs. The plasma physics, engineering, and economic implications of high aspect ratio tokamaks were accessed in the context of extended burn operation. Plasma startup and burn parameters were addressed using a one-dimensional transport code. The pulsed electrical power requirements for the poloidal field system, which have a major impact on reactor economics, were minimized by optimizing the field in the ohmic heating coil and the wave shape of the ohmic heating discharge. A high aspect ratio reference reactor was chosen and configured

  3. Plasma boundary phenomena in tokamaks

    International Nuclear Information System (INIS)

    Stangeby, P.C.

    1989-06-01

    The focus of this review is on processes occurring at the edge, and on the connection between boundary plasma - the scrape-off layer (SOL) and the radiating layer - and central plasma processes. Techniques used for edge diagnosis are reviewed and basic experimental information (n e and T e ) is summarized. Simple models of the SOL are summarized, and the most important effects of the boundary plasma - the influence on the fuel particles, impurities, and energy - on tokamak operation dealt with. Methods of manipulating and controlling edge conditions in tokamaks and the experimental data base for the edge during auxiliary heating of tokamaks are reviewed. Fluctuations and asymmetries at the edge are also covered. (9 tabs., 134 figs., 879 refs.)

  4. The European Integrated Tokamak Modelling (ITM) effort: achievements and first physics results

    International Nuclear Information System (INIS)

    Falchetto, G.L.; Nardon, E.; Artaud, J.F.; Basiuk, V.; Huynh, Ph.; Imbeaux, F.; Coster, D.; Scott, B.D.; Coelho, R.; Alves, L.L.; Bizarro, João P.S.; Ferreira, J.; Figueiredo, A.; Figini, L.; Nowak, S.; Farina, D.; Kalupin, D.; Boulbe, C.; Faugeras, B.; Dinklage, A.

    2014-01-01

    A selection of achievements and first physics results are presented of the European Integrated Tokamak Modelling Task Force (EFDA ITM-TF) simulation framework, which aims to provide a standardized platform and an integrated modelling suite of validated numerical codes for the simulation and prediction of a complete plasma discharge of an arbitrary tokamak. The framework developed by the ITM-TF, based on a generic data structure including both simulated and experimental data, allows for the development of sophisticated integrated simulations (workflows) for physics application. The equilibrium reconstruction and linear magnetohydrodynamic (MHD) stability simulation chain was applied, in particular, to the analysis of the edge MHD stability of ASDEX Upgrade type-I ELMy H-mode discharges and ITER hybrid scenario, demonstrating the stabilizing effect of an increased Shafranov shift on edge modes. Interpretive simulations of a JET hybrid discharge were performed with two electromagnetic turbulence codes within ITM infrastructure showing the signature of trapped-electron assisted ITG turbulence. A successful benchmark among five EC beam/ray-tracing codes was performed in the ITM framework for an ITER inductive scenario for different launching conditions from the equatorial and upper launcher, showing good agreement of the computed absorbed power and driven current. Selected achievements and scientific workflow applications targeting key modelling topics and physics problems are also presented, showing the current status of the ITM-TF modelling suite. (paper)

  5. Nuclear fusion research at Tokamak Energy Ltd

    International Nuclear Information System (INIS)

    Windridge, Melanie J.; Gryaznevich, Mikhail; Kingham, David

    2017-01-01

    Tokamak Energy's approach is close to the mainstream of nuclear fusion, and chooses a spherical tokamak, which is an economically developed form of Tokamak reactor design, as research subjects together with a high-temperature superconducting magnet. In the theoretical prediction, it is said that spherical tokamak can make tokamak reactor's scale compact compared with ITER or DEMO. The dependence of fusion energy multiplication factor on reactor size is small. According to model studies, it has been found that the center coil can be protected from heat and radiation damage even if the neutron shielding is optimized to 35 cm instead of 1 m. As a small tokamak with a high-temperature superconducting magnet, ST25 HTS, it demonstrated in 2015 continuous operation for more than 24 hours as a world record. Currently, this company is constructing a slightly larger ST40 type, and it is scheduled to start operation in 2017. ST40 is designed to demonstrate that it can realize a high magnetic field with a compact size and aims at attaining 8-10 keV (reaching the nuclear fusion reaction temperature at about 100 million degrees). This company will verify the startup and heating technology by the coalescence of spherical tokamak expected to have plasma current of 2 MA, and will also use 2 MW of neutral particle beam heating. In parallel with ST40, it is promoting a development program for high-temperature superconducting magnet. (A.O.)

  6. Na velikosti nezáleží - je to fraktální

    Czech Academy of Sciences Publication Activity Database

    Řípa, Milan

    2014-01-01

    Roč. 7, červen (2014) Institutional support: RVO:61389021 Keywords : fusion * tokamak * fractal * turbulence * Bohm diffusion Subject RIV: BL - Plasma and Gas Discharge Physics http://3pol.cz/1614-na-velikosti-nezalezi-je-to-fraktalni-aneb-slunecni-termojaderny-reaktor

  7. Empiricial scaling of inter-ELM power widths in ASDEX Upgrade and JET

    Energy Technology Data Exchange (ETDEWEB)

    Eich, T., E-mail: teich@ipp.mpg.de [Max-Planck-Institut für Plasmaphysik, EURATOM Association, Boltzmannstr. 2, D-85748 Garching (Germany); Sieglin, B.; Scarabosio, A.; Herrmann, A.; Kallenbach, A. [Max-Planck-Institut für Plasmaphysik, EURATOM Association, Boltzmannstr. 2, D-85748 Garching (Germany); Matthews, G.F. [EURATOM/CCFE Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Jachmich, S. [ERM-KMS, EURATOM Association, Brussels (Belgium); Brezinsek, S.; Rack, M. [IEK-4, Forschungszentrum Jülich, EURATOM Association (Germany); Goldston, R.J. [Princeton Plasma Physics Labaratory, Princeton, NJ 08543 (United States)

    2013-07-15

    The SOL power decay length (λ{sub q}) deduced from analysis of fully attached divertor heat load profiles from two tokamaks, JET and ASDEX Upgrade with carbon plasma facing components, are presented. Interpretation of the target heat load profiles is performed by using a 1D-fit function which disentangles the upstream λ{sub q} and an effective diffusion in the divertor (S), the latter essentially acting as a power spreading parameter in the divertor volume. It is shown that the so called integral decay length λ{sub int} is approximately given by λ{sub int}≈λ{sub q}+1.64×S. An empirical scaling reveals parametric dependency λ{sub q}/mm≃0.9·B{sub T}{sup -0.7}q{sub cyl}{sup 1.2}P{sub SOL}{sup 0}R{sub geo}{sup 0} for type-I ELMy H-modes. Extrapolation to ITER gives λ{sub q}≃1 mm. Recent measurements in JET-ILW and from ASDEX Upgrade full-W confirm the results. It is shown that a regression for the divertor power spreading parameter S is not yet possible due to the large effect of different divertor geometries of JET and ASDEX Upgrade Divertor-I and Divertor-IIb.

  8. Tokamak simulation code manual

    International Nuclear Information System (INIS)

    Chung, Moon Kyoo; Oh, Byung Hoon; Hong, Bong Keun; Lee, Kwang Won

    1995-01-01

    The method to use TSC (Tokamak Simulation Code) developed by Princeton plasma physics laboratory is illustrated. In KT-2 tokamak, time dependent simulation of axisymmetric toroidal plasma and vertical stability have to be taken into account in design phase using TSC. In this report physical modelling of TSC are described and examples of application in JAERI and SERI are illustrated, which will be useful when TSC is installed KAERI computer system. (Author) 15 refs., 6 figs., 3 tabs

  9. Mercier criterion for high-β tokamaks

    International Nuclear Information System (INIS)

    Galvao, R.M.O.

    1984-01-01

    An expression, for the application of the Mercier criterion to numerical studies of diffuse high-β tokamaks (β approximatelly Σ,q approximatelly 1), which contains only leading order contributions in the high-β tokamak approximation is derived. (L.C.) [pt

  10. Tokamak Physics Experiment (TPX) design

    International Nuclear Information System (INIS)

    Schmidt, J.A.

    1995-01-01

    TPX is a national project involving a large number of US fusion laboratories, universities, and industries. The element of the TPX requirements that is a primary driver for the hardware design is the fact that TPX tokamak hardware is being designed to accommodate steady state operation if the external systems are upgraded from the 1,000 second initial operation. TPX not only incorporates new physics, but also pioneers new technologies to be used in ITER and other future reactors. TPX will be the first tokamak with fully superconducting magnetic field coils using advanced conductors, will have internal nuclear shielding, will use robotics for machine maintenance, and will remove the continuous, concentrated heat flow from the plasma with new dispersal techniques and with special materials that are actively cooled. The Conceptual Design for TPX was completed during Fiscal Year 1993. The Preliminary Design formally began at the beginning of Fiscal Year 1994. Industrial contracts have been awarded for the design, with options for fabrication, of the primary tokamak hardware. A large fraction of the design and R and D effort during FY94 was focused on the tokamak and in turn on the tokamak magnets. The reason for this emphasis is because the magnets require a large design and R and D effort, and are critical to the project schedule. The magnet development is focused on conductor development, quench protection, and manufacturing R and D. The Preliminary Design Review for the Magnets is planned for fall, 1995

  11. Steady State Advanced Tokamak (SSAT): The mission and the machine

    International Nuclear Information System (INIS)

    Thomassen, K.; Goldston, R.; Nevins, B.; Neilson, H.; Shannon, T.; Montgomery, B.

    1992-03-01

    Extending the tokamak concept to the steady state regime and pursuing advances in tokamak physics are important and complementary steps for the magnetic fusion energy program. The required transition away from inductive current drive will provide exciting opportunities for advances in tokamak physics, as well as important impetus to drive advances in fusion technology. Recognizing this, the Fusion Policy Advisory Committee and the US National Energy Strategy identified the development of steady state tokamak physics and technology, and improvements in the tokamak concept, as vital elements in the magnetic fusion energy development plan. Both called for the construction of a steady state tokamak facility to address these plan elements. Advances in physics that produce better confinement and higher pressure limits are required for a similar unit size reactor. Regimes with largely self-driven plasma current are required to permit a steady-state tokamak reactor with acceptable recirculating power. Reliable techniques of disruption control will be needed to achieve the availability goals of an economic reactor. Thus the central role of this new tokamak facility is to point the way to a more attractive demonstration reactor (DEMO) than the present data base would support. To meet the challenges, we propose a new ''Steady State Advanced Tokamak'' (SSAT) facility that would develop and demonstrate optimized steady state tokamak operating mode. While other tokamaks in the world program employ superconducting toroidal field coils, SSAT would be the first major tokamak to operate with a fully superconducting coil set in the elongated, divertor geometry planned for ITER and DEMO

  12. Study of heat fluxes on plasma facing components in a tokamak from measurements of temperature by infrared thermography

    International Nuclear Information System (INIS)

    Daviot, R.

    2010-05-01

    The goal of this thesis is the development of a method of computation of those heat loads from measurements of temperature by infrared thermography. The research was conducted on three issues arising in current tokamaks but also future ones like ITER: the measurement of temperature on reflecting walls, the determination of thermal properties for deposits observed on the surface of tokamak components and the development of a three-dimensional, non-linear computation of heat loads. A comparison of several means of pyrometry, monochromatic, bi-chromatic and photothermal, is performed on an experiment of temperature measurement. We show that this measurement is sensitive to temperature gradients on the observed area. Layers resulting from carbon deposition by the plasma on the surface of components are modeled through a field of equivalent thermal resistance, without thermal inertia. The field of this resistance is determined, for each measurement points, from a comparison of surface temperature from infrared thermographs with the result of a simulation, which is based on a mono-dimensional linear model of components. The spatial distribution of the deposit on the component surface is obtained. Finally, a three-dimensional and non-linear computation of fields of heat fluxes, based on a finite element method, is developed here. Exact geometries of the component are used. The sensitivity of the computed heat fluxes is discussed regarding the accuracy of the temperature measurements. This computation is applied to two-dimensional temperature measurements of the JET tokamak. Several components of this tokamak are modeled, such as tiles of the divertor, upper limiter and inner and outer poloidal limiters. The distribution of heat fluxes on the surface of these components is computed and studied along the two main tokamak directions, poloidal and toroidal. Toroidal symmetry of the heat loads from one tile to another is shown. The influence of measurements spatial resolution

  13. Using plasma waves to create in tokamaks the necessary quasi-stationary conditions for controlled fusion

    International Nuclear Information System (INIS)

    Moreau, D.

    1993-04-01

    It is studied, on the one hand, how using hybrid waves with frequency near from lower hybrid frequency in fusion plasma. Works about coupling waves in plasma (chap.I), their propagation and response of the plasma to the absorption of the waves (chap.II). This method is the most effective until today. Because of limits, it has been investigated, on the other hand, fast magnetosonic wave to control current density in the centre of the discharge in a reactor or a very hot plasma. Theoretical study (chap.III) and experimental results (chap.IV) are presented. Experiments are in progress or planned in following tokamaks: D3-D (USA), JET (Europe), TORE SUPRA (France), JT-60 (Japan). figs. refs. tabs

  14. Summary of the 1982 small tokamak users meeting

    International Nuclear Information System (INIS)

    Sprott, J.C.

    1982-11-01

    On November 1, 1982, the sixth in a series of approximately annual meetings of the users of small tokamaks was held in conjunction with the APS Division of Plasma Physics meeting at New Orleans. The meeting lasted three hours, with 34 people attending. The interest was on strengthening the ties between the small tokamaks and the large tokamaks. Accordingly, the latest meeting was dedicated to this theme, and in contrast to previous meetings, a few representatives from the large tokamaks were invited to attend and make presentations. Summaries of the various talks are included

  15. Magnetic confinement by Tokamak: physical aspects

    International Nuclear Information System (INIS)

    Tachon, J.

    1980-01-01

    After describing the Tokamak configuration concept, the author provides an analysis of the principal physical aspects of this type of installation and concludes by estimating that the Tokamak concept is a 'plausible candidate' as a means of producing controlled thermonuclear fusion [fr

  16. Tokamak research in the Soviet Union

    International Nuclear Information System (INIS)

    Strelkov, V.S.

    1981-01-01

    Important milestones on the way to the tokamak fusion reactor are recapitulated. Soviet tokamak research concentrated at the I.V. Kurchatov Institute in Moscow, the A.F. Ioffe Institute in Leningrad and the Physical-Technical Institute in Sukhumi successfully provides necessary scientific and technological data for reactor design. Achievments include, the successful operation of the first tokamak with superconducting windings (T-7) and the gyrotron set for microwave plasma heating in the T-10 tokamak. The following problems have intensively been studied: Various methods of additional plasma heating, heat and particle transport, and impurity control. The efficiency of electron-cyclotron resonance heating was demonstrated. In the Joule heating regime, both the heat conduction and diffusion rates are anomalously high, but the electron heat conduction rate decreases with increasing plasma density. Progress in impurity control makes it possible to obtain a plasma with effective charge approaching unity. (J.U.)

  17. Neutral beam in ALVAND IIC tokamak

    International Nuclear Information System (INIS)

    Ghrannevisse, M.; Moradshahi, M.; Avakian, M.

    1992-01-01

    Neutral beams have a wide application in tokamak experiments. It used to heat; fuel; adjust electric potentials in plasmas and diagnose particles densities and momentum distributions. It may be used to sustain currents in tokamaks to extend the pulse length. A 5 KV; 500 mA ion source has been constructed by plasma physics group, AEOI and it used to produce plasma and study the plasma parameters. Recently this ion source has been neutralized and it adapted to a neutral beam source; and it used to heat a cylindrical DC plasma and the plasma of ALVAND IIC Tokamak which is a small research tokamak with a minor radius of 12.6 cm, and a major radius of 45.5 cm. In this paper we report the neutralization of the ion beam and the results obtained by injection of this neutral beam into plasmas. (author) 2 refs., 4 figs

  18. Modeling of sawtooth destabilization during radio-frequency heating experiments in tokamak plasmas

    International Nuclear Information System (INIS)

    McClements, K.G.; Dendy, R.O.; Hastie, R.J.; Martin, T.J.

    1996-01-01

    Sawtooth oscillations in tokamaks have been stabilized using ion cyclotron resonance heating (ICRH), but often reappear while ICRH continues. It is shown that the reappearance of sawteeth during one particular ICRH discharge in the Joint European Torus (JET) [Campbell et al., Phys. Rev. Lett. 60, 2148 (1988)] was correlated with a change of sign in the energy δW associated with m=1 internal kink displacements. To compute δW, a new analytical model is used for the distribution function of heated minority ions, which is consistent with Fokker endash Planck simulations of ICRH. Minority ions have a stabilizing influence, arising from third adiabatic invariant conservation, but also contribute to a destabilizing shift of magnetic flux surfaces. As the minor radius of the q=1 surface rises, the stabilizing influence of minority ions diminishes, and the shape of the plasma cross section becomes increasingly important. It is shown that an increase in ICRH power can destabilize the kink mode: this is consistent with observations of sawteeth in JET discharges with varying levels of ICRH. It is suggested that the sawtooth-free period could be prolonged by minimizing the vertical extent of the ICRH power deposition profile.1996 American Institute of Physics

  19. Diagnostics for the Rijnhuizen Tokamak Project

    NARCIS (Netherlands)

    Donne, A. J. H.

    1994-01-01

    The research program of the Rijnhuizen Tokamak Project is concentrated on the study of plasma transport processes. The RTP tokamak is therefore equipped with an extensive set of multichannel diagnostics, including a 19-channel FIR interferometer, a 20-channel heterodyne ECE system, an 80-channel

  20. Plasma position control in TCABR Tokamak

    International Nuclear Information System (INIS)

    Galvao, R.M.O.; Kuznetsov, Yu. K.; Nascimento, I.C.; Fonseca, A.M.M.; Silva, R.P. da; Ruchko, L.F.; Tuszel, A.G.; Reis, A.P. dos; Sanada, E.K.

    1998-01-01

    The plasma control position in the TCABR tokamak is described. The TCA tokamak was transferred from the Centre de Recherches en Physique des Plasmas, Lausanne, to the Institute of Physics of University of Sao Paulo, renamed TCABR (α=0.18 m, R = 0.62 m, B = 1 T,I p = 100 kA). The control system was reconstructed using mainly components obtained from the TCA tokamak. A new method of plasma position determination is used in TCABR to improve its accuracy. A more detailed theoretical analysis of the feed forward and feedback control is performed as compared with. (author)

  1. Global gyrokinetic simulation of tokamak transport

    International Nuclear Information System (INIS)

    Furnish, G.; Horton, W.; Kishimoto, Y.; LeBrun, M.J.; Tajima, T.

    1998-10-01

    A kinetic simulation code based on the gyrokinetic ion dynamics in global general metric (including a tokamak with circular or noncircular cross-section) has been developed. This gyrokinetic simulation is capable of examining the global and semi-global driftwave structures and their associated transport in a tokamak plasma. The authors investigate the property of the ion temperature gradient (ITG) or η i (η i ≡ ∂ ell nT i /∂ ell n n i ) driven drift waves in a tokamak plasma. The emergent semi-global drift wave modes give rise to thermal transport characterized by the Bohm scaling

  2. Fast IR diodes thermometer for tokamak

    International Nuclear Information System (INIS)

    Chen Xiangbo

    2001-01-01

    A 30 channel fast IR pyrometry array has been constructed for tokamak, which has 0.5 μs time response, 10 mm diameter spatial resolution and 5 degree C temperature resolution. The temperature measuring range is from 250 degree C to 1200 degree C. The two dimensional temperature profiles of the first wall during both major and minor disruptions can be measured with an accuracy of about 1% measuring temperature, which is adequate for tokamak experiments. This gives a very useful tool for the disruption study, especially for the divertor physics and edge heat flux research on tokamak and other magnetic confinement devices

  3. Module of lithium divertor for KTM tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Lyublinski, I., E-mail: yublinski@yandex.ru [FSUE ' Red Star' , Moscow (Russian Federation); Vertkov, A.; Evtikhin, V.; Balakirev, V.; Ionov, D.; Zharkov, M. [FSUE ' Red Star' , Moscow (Russian Federation); Tazhibayeva, I. [IAE NNC RK, Kurchatov (Kazakhstan); Mirnov, S. [TRINITI, Troitsk, Moscow Region (Russian Federation); Khomiakov, S.; Mitin, D. [OJSC Dollezhal Institute, Moscow (Russian Federation); Mazzitelli, G. [ENEA RC Frascati (Italy); Agostini, P. [ENEA RC Brasimone (Italy)

    2012-10-15

    steady-state operating lithium divertor module project for Kazakhstan tokamak KTM. At present the lithium divertor module for KTM tokamak is under development in the framework of ISTC project no. K-1561. Initial heating up to 200 Degree-Sign C and lithium surface temperature stabilization during plasma interaction in the range of 350-550 Degree-Sign C will be provided by external system for thermal stabilization due to circulation of the Na-K heat transfer media. Lithium filled tungsten felt is offered as the base plasma facing material of divertor. Development, creation and experimental research of lithium divertor model for KTM will allow to solve existing problems and to fulfill the basic approaches to designing of lithium divertor and in-vessel elements of new fusion reactor generation, to investigate plasma physics aspects of lithium influence, to develop technology of work with lithium in tokamak conditions. Results of this project addresses to the progress in the field of fusion neutrons source and fusion energy source creation.

  4. Prospects for Tokamak Fusion Reactors

    International Nuclear Information System (INIS)

    Sheffield, J.; Galambos, J.

    1995-01-01

    This paper first reviews briefly the status and plans for research in magnetic fusion energy and discusses the prospects for the tokamak magnetic configuration to be the basis for a fusion power plant. Good progress has been made in achieving fusion reactor-level, deuterium-tritium (D-T) plasmas with the production of significant fusion power in the Joint European Torus (up to 2 MW) and the Tokamak Fusion Test Reactor (up to 10 MW) tokamaks. Advances on the technologies of heating, fueling, diagnostics, and materials supported these achievements. The successes have led to the initiation of the design phases of two tokamaks, the International Thermonuclear Experimental Reactor (ITER) and the US Toroidal Physics Experiment (TPX). ITER will demonstrate the controlled ignition and extended bum of D-T plasmas with steady state as an ultimate goal. ITER will further demonstrate technologies essential to a power plant in an integrated system and perform integrated testing of the high heat flux and nuclear components required to use fusion energy for practical purposes. TPX will complement ITER by testing advanced modes of steady-state plasma operation that, coupled with the developments in ITER, will lead to an optimized demonstration power plant

  5. Analysis and modelling of power modulation experiments in JET plasmas with internal transport barriers

    Energy Technology Data Exchange (ETDEWEB)

    Marinoni, A [Politecnico di Milano, dipartimento di Ingegneria Nucleare, Milano (Italy); Mantica, P [Istituto di Fisica del Plasma, Euratom-ENEA-CNR Association, Milan (Italy); Eester, D Van [LPP-ERM/KMS, Association EURATOM-Belgian State, TEC, B-1000 Brussels (Belgium); Imbeaux, F [Association EURATOM-CEA, CEA/DSM/DRFC, CEA Cadarache, 13108 Saint Paul lez Durance (France); Mantsinen, M [Helsinki University of Technology, Association Euratom-Tekes, PO Box 2200 (Finland); Hawkes, N [Euratom-UKAEA Fusion Association, Culham Science Centre, Abingdon, Oxon (United Kingdom); Joffrin, E [Association EURATOM-CEA, CEA/DSM/DRFC, CEA Cadarache, 13108 Saint Paul lez Durance (France); Kiptily, V [Euratom-UKAEA Fusion Association, Culham Science Centre, Abingdon, Oxon (United Kingdom); Pinches, S D [Max Plank Institut fur Plasmaphysik, Euratom Association, Garching (Germany); Salmi, A [Helsinki University of Technology, Association Euratom-Tekes, PO Box 2200 (Finland); Sharapov, S [Euratom-UKAEA Fusion Association, Culham Science Centre, Abingdon, Oxon (United Kingdom); Voitsekhovitch, I [Euratom-UKAEA Fusion Association, Culham Science Centre, Abingdon, Oxon (United Kingdom); Vries, P de [FOM Institut voor Plasmafysica, Association Euratom-FOM, Nieuwegein, The (Netherlands); Zastrow, K D [Euratom-UKAEA Fusion Association, Culham Science Centre, Abingdon, Oxon (United Kingdom)

    2006-10-15

    Understanding the physics of internal transport barriers (ITBs) is a crucial issue in developing ITER relevant advanced tokamak scenarios. To gain new information on ITBs, RF power modulation experiments, mainly devoted to the study of electron heat transport through ITBs, have been performed on the JET tokamak. The main physics results have been reported in [1]. The present paper describes in detail the data analysis and numerical modelling work carried out for the interpretation of the experiments. ITBs located in the negative shear region behave as localized insulating layers able to stop the heat wave propagation, thus implying that the ITB is a region of low diffusivity characterized by a loss of stiffness. Various sources of spurious effects affecting the interpretation of the results are analysed and discussed. First principle based models have so far failed to predict the temperature profile in the first place, which prevented their application to modulation results, while empirical transport models have been set up and reproduce the major part of the data.

  6. Presheath profiles in simulated tokamak edge plasmas

    International Nuclear Information System (INIS)

    LaBombard, B.; Conn, R.W.; Hirooka, Y.; Lehmer, R.; Leung, W.K.; Nygren, R.E.; Ra, Y.; Tynan, G.

    1988-04-01

    The PISCES plasma surface interaction facility at UCLA generates plasmas with characteristics similar to those found in the edge plasmas of tokamaks. Steady state magnetized plasmas produced by this device are used to study plasma-wall interaction phenomena which are relevant to tokamak devices. We report here progress on some detailed investigations of the presheath region that extends from a wall surface into these /open quotes/simulated tokamak/close quotes/ edge plasma discharges along magnetic field lines

  7. Robust Sliding Mode Control for Tokamaks

    Directory of Open Access Journals (Sweden)

    I. Garrido

    2012-01-01

    Full Text Available Nuclear fusion has arisen as an alternative energy to avoid carbon dioxide emissions, being the tokamak a promising nuclear fusion reactor that uses a magnetic field to confine plasma in the shape of a torus. However, different kinds of magnetohydrodynamic instabilities may affect tokamak plasma equilibrium, causing severe reduction of particle confinement and leading to plasma disruptions. In this sense, numerous efforts and resources have been devoted to seeking solutions for the different plasma control problems so as to avoid energy confinement time decrements in these devices. In particular, since the growth rate of the vertical instability increases with the internal inductance, lowering the internal inductance is a fundamental issue to address for the elongated plasmas employed within the advanced tokamaks currently under development. In this sense, this paper introduces a lumped parameter numerical model of the tokamak in order to design a novel robust sliding mode controller for the internal inductance using the transformer primary coil as actuator.

  8. Three novel tokamak plasma regimes in TFTR

    International Nuclear Information System (INIS)

    Furth, H.P.

    1985-10-01

    Aside from extending ''standard'' ohmic and neutral beam heating studies to advanced plasma parameters, TFTR has encountered a number of special plasma regimes that have the potential to shed new light on the physics of tokamak confinement and the optimal design of future D-T facilities: (1) High-powered, neutral beam heating at low plasma densities can maintain a highly reactive hot-ion population (with quasi-steady-state beam fueling and current drive) in a tokamak configuration of modest bulk-plasma confinement requirements. (2) Plasma displacement away from limiter contact lends itself to clarification of the role of edge-plasma recycling and radiation cooling within the overall pattern of tokamak heat flow. (3) Noncentral auxiliary heating (with a ''hollow'' power-deposition profile) should serve to raise the central tokamak plasma temperature without deterioration of central region confinement, thus facilitating the study of alpha-heating effects in TFTR. The experimental results of regime (3) support the theory that tokamak profile consistency is related to resistive kink stability and that the global energy confinement time is determined by transport properties of the plasma edge region

  9. Internal disruption in tokamaks

    International Nuclear Information System (INIS)

    Kuvshinov, B.N.; Savrukhin, P.V.

    1990-01-01

    A review of results of experimental and theoretical investigations of internal disruption in tokamaks is given. Specific features of various types of saw-tooth oscillations are described and their classification is performed. Theoretical models of the process of development of internal disruption instability are discussed. Effect of internal disruption on parameters of plasma, confined in tokamak, is considered. Scalings of period and amplitude of saw-tooth oscillations, as well as version radius are presented. Different methods for stabilizing instability of internal disruption are described

  10. Internal disruptions in tokamaks

    International Nuclear Information System (INIS)

    Kuvshinov, B.N.; Savrukhin, P.V.

    1990-01-01

    Experimental and theoretical studies of the phenomenon of internal disruptions in tokamaks are reviewed. A classification scheme is introduced and the features of different types of sawtooth oscillations are described. A theoretical model for the development of the internal disruption instability is discussed. The effect of internal disruptions on the parameters of plasma confined in tokamaks is discussed. Scaling laws for the period and amplitude of sawtooth oscillations, as well as for the inversion radius, are presented. Different methods of stabilizing the internal disruption instability are described

  11. First Production of C60 Nanoparticle Plasma Jet for Study of Disruption Mitigation for ITER

    Science.gov (United States)

    Bogatu, I. N.; Thompson, J. R.; Galkin, S. A.; Kim, J. S.; Brockington, S.; Case, A.; Messer, S. J.; Witherspoon, F. D.

    2012-10-01

    Unique fast response and large mass-velocity delivery of nanoparticle plasma jets (NPPJs) provide a novel application for ITER disruption mitigation, runaway electrons diagnostics and deep fueling. NPPJs carry a much larger mass than usual gases. An electromagnetic plasma gun provides a very high injection velocity (many km/s). NPPJ has much higher ram pressure than any standard gas injection method and penetrates the tokamak confining magnetic field. Assimilation is enhanced due to the NP large surface-to-volume ratio. Radially expanding NPPJs help achieving toroidal uniformity of radiation power. FAR-TECH's NPPJ system was successfully tested: a coaxial plasma gun prototype (˜35 cm length, 96 kJ energy) using a solid state TiH2/C60 pulsed power cartridge injector produced a hyper-velocity (>4 km/s), high-density (>10^23 m-3), C60 plasma jet in ˜0.5 ms, with ˜1-2 ms overall response-delivery time. We present the TiH2/C60 cartridge injector output characterization (˜180 mg of sublimated C60 gas) and first production results of a high momentum C60 plasma jet (˜0.6 g.km/s).

  12. Project and analysis of the toroidal magnetic field production circuits and the plasma formation of the ETE (Spherical Tokamak Experiment) tokamak; Projeto e analise dos circuitos de producao de campo magnetico toroidal e de formacao do plasma do Tokamak ETE (Experimento Tokamak Esferico)

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, Luis Filipe F.P.W.; Bosco, Edson del

    1994-12-31

    This report presents the project and analysis of the circuit for production of the toroidal magnetic field in the Tokamak ETE (Spherical Tokamak Experiment). The ETE is a Tokamak with a small-aspect-ratio parameter to be used for studying the plasma physics for the research on thermonuclear fusion. This machine is being constructed at the Laboratorio Associado de Plasma (LAP) of the Instituto Nacional de Pesquisas Espaciais (INPE) in Sao Jose dos Campos, SP, Brazil. (author). 20 refs., 39 figs., 4 tabs.

  13. Conceptual design for a bulk tungsten divertor tile in JET

    International Nuclear Information System (INIS)

    Mertens, Ph.; Hirai, T.; Linke, J.; Neubauer, O.; Pintsuk, G.; Philipps, V.; Sadakov, S.; Samm, U.; Schweer, B.

    2007-01-01

    The ITER-like Wall project (ILW) for JET aims at providing the plasma chamber of the tokamak with an environment of mixed materials which will be relevant for the actual first wall construction on ITER. Tungsten plays a key role in the divertor cladding. For the central tile, also called LB-SRP for 'load-bearing septum replacement plate', bulk tungsten is envisaged in order to cope with the high heat loads expected (up to 10 MW/m 2 for 10 s). The outer strike-point in the divertor will be positioned on this tile for the most relevant configurations. Forschungszentrum Juelich (FZJ) has developed a conceptual design based on an assembly of tungsten blades or lamellae. An appropriate interface with the base carrier of JET, on which modules of two tiles are positioned and fixed by remote handling procedures, is a substantial part of the integral design. Important issues are the electromagnetic forces and expected temperature distributions. Material choices combine tungsten, TZM TM , Inconel and ceramic parts. The completed design has been finalised in a proposal to the ILW project, with utmost ITER-relevance

  14. Tokamak pump limiters

    International Nuclear Information System (INIS)

    Conn, R.W.

    1984-05-01

    Recent experiments with a scoop limiter without active internal pumping have been carried out in the PDX tokamak with up to 6MW of auxiliary neutral beam heating. Experiments have also been done with a rotating head pump limiter in the PLT tokamak in conjunction with RF plasma heating. Extensive experiments have been done in the ISX-B tokamak and first experiments have been completed with the ALT-I limiter in TEXTOR. The pump limiter modules in these latter two machines have internal getter pumping. Experiments in ISX-B are with ohmic and auxiliary neutral beam heating. The results in ISX-B and TEXTOR show that active density control and particle removal is achieved with pump limiters. In ISX-B, the boundary layer (or scape-off layer) plasma partially screens the core plasma from gas injection. In both ISX-B and TEXTOR, the pressure internal to the module scales linearly with plasma density but in ISX-B, with neutral beam injection, a nonlinear increase is observed at the highest densities studied. Plasma plugging is the suspected cause. Results from PDX suggest that a region may exist in which core plasma energy confinement improves using a pump limiter during neutral beam injection. Asymmetric radial profiles and an increased edge electron temperature are observed in discharges with improved confinement. The injection of small amounts of neon into ISX-B has more clearly shown an improved electron core energy confinement during neutral beam injection. While carried out with a regular limiter, this Z-mode of operation is ideal for use with pump limiters and should be a way to achieve energy confinement times similar to values for H-mode tokamak plasmas. The implication of all these results for the design of a reactor pump limiter is described

  15. Tokamak pump limiters

    International Nuclear Information System (INIS)

    Conn, R.W.; California Univ., Los Angeles

    1984-01-01

    Recent experiments with a scoop limiter without active internal pumping have been carried out in the PDX tokamak with up to 6 MW of auxiliary neutral beam heating. Experiments have also been performed with a rotating head pump limiter in the PLT tokamak in conjunction with RF plasma heating. Extensive experiments have been done in the ISX-B tokamak and first experiments have been completed with the ALT-I limiter in TEXTOR. The pump limiter modules in these latter two machines have internal getter pumping. Experiments in ISX-B are with ohmic and auxiliary neutral beam heating. The results in ISX-B and TEXTOR show that active density control and particle removal is achieved with pump limiters. In ISX-B, the boundary layer (or scrape-off layer) plasma partially screens the core plasma from gas injection. In both ISX-B and TEXTOR, the pressure internal to the module scales linearly with plasma density but in ISX-B, with neutral beam injection, a nonlinear increase is observed at the highest densities studied. Plasma plugging is the suspected cause. Results from PDX suggest that a regime may exist in which core plasma energy confinement improves using a pump limiter during neutral beam injection. Asymmetric radial profiles and an increased edge electron temperature are observed in discharges with improved confinement. The injection of small amounts of neon into ISX-B has more clearly shown an improved electron core energy confinement during neutral beam injection. While carried out with a regular limiter, this 'Z-mode' of operation is ideal for use with pump limiters and should be a way to achieve energy confinement times similar to values for H-mode tokamak plasmas. The implication of all these results for the design of a reactor pump limiter is described. (orig.)

  16. Estimation of Zeff in Novillo Tokamak

    International Nuclear Information System (INIS)

    Valencia, R.; Olayo, G.; Cruz, G.; Lopez, R.; Chavez, E.; Melendez, L.; Flores, A.; Gaytan, E.

    1996-01-01

    We estimated the Z eff in the Novillo Tokamak after having applied a HeGDC process through two different methods: anomaly factor and mass spectrometry. The first one gave a Z eff value of 2.07 for a tokamak discharge of 4350 A plasma current and 3 V of loop voltage. By mass spectrometry 30 s after the discharge had finished a Z eff of 4.19 was obtained for the same discharge. By mass spectrometry we observed that the Z eff value is a time function. Furthermore this method is helpful for evaluating the level of impurities after many discharges in Novillo Tokamak. (orig.)

  17. Study of wall conditioning in tokamaks with application to ITER

    International Nuclear Information System (INIS)

    Kogut, Dmitri

    2014-01-01

    Thesis is devoted to studies of performance and efficiency of wall conditioning techniques in fusion reactors, such as ITER. Conditioning is necessary to control the state of the surface of plasma facing components to ensure plasma initiation and performance. Conditioning and operation of the JET tokamak with ITER-relevant material mix is extensively studied. A 2D model of glow conditioning discharges is developed and validated; it predicts reasonably uniform discharges in ITER. In the nuclear phase of ITER operation conditioning will be needed to control tritium inventory. It is shown here that isotopic exchange is an efficient mean to eliminate tritium from the walls by replacing it with deuterium. Extrapolations for tritium removal are comparable with expected retention per a nominal plasma pulse in ITER. A 1D model of hydrogen isotopic exchange in beryllium is developed and validated. It shows that fluence and temperature of the surface influence efficiency of the isotopic exchange. (author) [fr

  18. Ideal MHD stability of internal kinks in circular and shaped tokamaks

    International Nuclear Information System (INIS)

    Luetjens, H.; Bondeson, A.; Vlad, G.

    1992-04-01

    Stability limits for the internal kink mode in tokamaks are calculated for different current profiles and plasma cross sections using ideal magnetohydrodynamics (MHD). The maximum stable poloidal beta at the q = 1 surface (β p ) is sensitive to the current profile, but for circular cross sections, it is typically between 0.1 and 0.2. Large aspect ratio theory gives similar predictions when the appropriate boundary conditions are applied at the plasma-vacuum surface. The pressure driven internal kink is significantly destabilized by ellipticity. For JET geometry, the β p -limit is typically between 0.05 and 0.1, but arbitrarily low limits can result if the shear is reduced at the q=1 surface. A large aspect ratio expansion of the Mercier criterion retaining the effects of ellipticity and triangularity is given to illustrate the destabilizing influence of ellipticity. (author) 17 figs., 16 refs

  19. Internal Transport Barrier triggering by rational magnetic flux surfaces in tokamaks

    International Nuclear Information System (INIS)

    Joffrin, E.H.

    2002-01-01

    The formation of Internal Transport Barriers (ITBs) has been experimentally associated with the presence of rational q-surfaces in both JET and ASDEX Upgrade. The triggering mechanisms are related to the occurrence of magneto-hydrodynamic (MHD) instabilities such as mode coupling or fishbone activity. These events could locally modify the poloidal velocity and increase transiently the shearing rate to values comparable to the linear growth rate of ITG modes. For reversed magnetic shear scenario, ITB emergence occurs preferentially when the minimum q reaches an integer value. In this case, transport effects localised in the vicinity of zero magnetic shear and close to rational q values may also contribute to the formation of ITBs. The role of rational q surfaces on ITB triggering stresses the importance of q profile control for advanced tokamak scenario and could contribute to lower substantially the access power to these scenarios in next step facilities. (author)

  20. Numerical Tokamak Project code comparison

    International Nuclear Information System (INIS)

    Waltz, R.E.; Cohen, B.I.; Beer, M.A.

    1994-01-01

    The Numerical Tokamak Project undertook a code comparison using a set of TFTR tokamak parameters. Local radial annulus codes of both gyrokinetic and gyrofluid types were compared for both slab and toroidal case limits assuming ion temperature gradient mode turbulence in a pure plasma with adiabatic electrons. The heat diffusivities were found to be in good internal agreement within ± 50% of the group average over five codes

  1. Confinement and diffusion in tokamaks

    International Nuclear Information System (INIS)

    McWilliams, R.

    1988-01-01

    The effect of electric field fluctuations on confinement and diffusion in tokamak is discussed. Based on the experimentally determined cross-field turbolent diffusion coefficient, D∼3.7*cT e /eB(δn i /n i ) rms which is also derived by a simple theory, the cross-field diffusion time, tp=a 2 /D, is calculated and compared to experimental results from 51 tokamak for standard Ohmic operation

  2. Numerical studies of edge localized instabilities in tokamaks

    International Nuclear Information System (INIS)

    Wilson, H.R.; Snyder, P.B.; Huysmans, G.T.A.; Miller, R.L.

    2002-01-01

    A new computational tool, edge localized instabilities in tokamaks equilibria (ELITE), has been developed to help our understanding of short wavelength instabilities close to the edge of tokamak plasmas. Such instabilities may be responsible for the edge localized modes observed in high confinement H-mode regimes, which are a serious concern for next step tokamaks because of the high transient power loads which they can impose on divertor target plates. ELITE uses physical insight gained from analytic studies of peeling and ballooning modes to provide an efficient way of calculating the edge ideal magnetohydrodynamic stability properties of tokamaks. This paper describes the theoretical formalism which forms the basis for the code

  3. Tokamak COMPASS

    Czech Academy of Sciences Publication Activity Database

    Řípa, Milan; Křenek, Petr

    2011-01-01

    Roč. 17, č. 1 (2011), s. 32-34 ISSN 1210-4612 Institutional research plan: CEZ:AV0Z20430508 Keywords : fusion * tokamak * Compass * Golem * Institute of Plasma Physics AVCR v.v * NBI * diagnostics Subject RIV: BL - Plasma and Gas Discharge Physics

  4. Development of thin foil Faraday collector as a lost alpha particle diagnostic for high yield D-T tokamak fusion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Van Belle, P; Jarvis, O N; Sadler, G J [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Cecil, F E [Colorado School of Mines, Golden, CO (United States)

    1994-07-01

    Alpha particle confinement is necessary for ignition of a D-T tokamak fusion plasma and for first wall protection. Due to high radiation backgrounds and temperatures, scintillators and semiconductor detectors may not be used to study alpha particles which are lost to the first wall during the D-T programs on JET and ITER. An alternative method of charged particle spectrometry capable of operation in these harsh environments, is proposed: it consists of thin foils of electrically isolated conductors with the flux of alpha particles determined by the positive current flowing from the foils. 2 refs., 3 figs.

  5. An enhanced tokamak startup model

    Science.gov (United States)

    Goswami, Rajiv; Artaud, Jean-François

    2017-01-01

    The startup of tokamaks has been examined in the past in varying degree of detail. This phase typically involves the burnthrough of impurities and the subsequent rampup of plasma current. A zero-dimensional (0D) model is most widely used where the time evolution of volume averaged quantities determines the detailed balance between the input and loss of particle and power. But, being a 0D setup, these studies do not take into consideration the co-evolution of plasma size and shape, and instead assume an unchanging minor and major radius. However, it is known that the plasma position and its minor radius can change appreciably as the plasma evolves in time to fill in the entire available volume. In this paper, an enhanced model for the tokamak startup is introduced, which for the first time takes into account the evolution of plasma geometry during this brief but highly dynamic period by including realistic one-dimensional (1D) effects within the broad 0D framework. In addition the effect of runaway electrons (REs) has also been incorporated. The paper demonstrates that the inclusion of plasma cross section evolution in conjunction with REs plays an important role in the formation and development of tokamak startup. The model is benchmarked against experimental results from ADITYA tokamak.

  6. Nonlinear transport processes in tokamak plasmas. I. The collisional regimes

    International Nuclear Information System (INIS)

    Sonnino, Giorgio; Peeters, Philippe

    2008-01-01

    An application of the thermodynamic field theory (TFT) to transport processes in L-mode tokamak plasmas is presented. The nonlinear corrections to the linear ('Onsager') transport coefficients in the collisional regimes are derived. A quite encouraging result is the appearance of an asymmetry between the Pfirsch-Schlueter (P-S) ion and electron transport coefficients: the latter presents a nonlinear correction, which is absent for the ions, and makes the radial electron coefficients much larger than the former. Explicit calculations and comparisons between the neoclassical results and the TFT predictions for Joint European Torus (JET) plasmas are also reported. It is found that the nonlinear electron P-S transport coefficients exceed the values provided by neoclassical theory by a factor that may be of the order 10 2 . The nonlinear classical coefficients exceed the neoclassical ones by a factor that may be of order 2. For JET, the discrepancy between experimental and theoretical results for the electron losses is therefore significantly reduced by a factor 10 2 when the nonlinear contributions are duly taken into account but, there is still a factor of 10 2 to be explained. This is most likely due to turbulence. The expressions of the ion transport coefficients, determined by the neoclassical theory in these two regimes, remain unaltered. The low-collisional regimes, i.e., the plateau and the banana regimes, are analyzed in the second part of this work

  7. Spherical tokamak development in Brazil

    International Nuclear Information System (INIS)

    Ludwig, G.O.; Del Bosco, E.; Ferreira, J.G.; Berni, L.A.; Oliveira, R.M.; Andrade, M.C.R.; Shibata, C.S.; Ueda, M.; Barroso, J.J.; Castro, P.J.; Barbosa, L.F.W.; Patire Junior, H.; The high-power microwave sources group

    2003-01-01

    This paper describes the general characteristics of spherical tokamaks, or spherical tori, with a brief overview of work in this area already performed or in progress at several institutions worldwide. The paper presents also the steps in the development of the ETE (Experimento Tokamak Esferico) project, its research program, technical characteristics and operating conditions as of December, 2002 at the Associated Plasma Laboratory (LAP) of the National Space Research Institute (INPE) in Brazil. (author)

  8. Enhancement of confinement in tokamaks

    International Nuclear Information System (INIS)

    Furth, H.P.

    1986-01-01

    The analysis begins by identifying a hypothetical model of tokamak confinement that is designed to take into account the conflict between Tsub(e)(r)-profile shapes arising from microscopic transport and J(r)-profile shapes required for gross stability. On the basis of this model, a number of hypothetical lines of advance are developed. Some TFTR experiments that may point the way to a particularly attractive type of tokamak reactor regime are discussed. (author)

  9. Spherical tokamak development in Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Ludwig, Gerson Otto; Bosco, Edson Del; Ferreira, Julio Guimaraes [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Lab. Associado de Plasma] (and others)

    2003-07-01

    The general characteristics of spherical tokamaks, or spherical tori, with a brief view of work in this area already performed or in progress at several institutions worldwide are described. The paper presents also the steps in the development of the ETE (Experiment Tokamak spheric) project, its research program, technical characteristics and operating conditions as of December, 2002 a the Associated Plasma Laboratory (LAP) of the National Space Research Institute (INPE) in Brazil. (author)

  10. Spherical tokamak development in Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Ludwig, G.O.; Del Bosco, E.; Ferreira, J.G.; Berni, L.A.; Oliveira, R.M.; Andrade, M.C.R.; Shibata, C.S.; Ueda, M.; Barroso, J.J.; Castro, P.J. [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Lab. Associado de Plasma; Barbosa, L.F.W. [Universidade do Vale do Paraiba (UNIVAP), Sao Jose dos Campos, SP (Brazil). Faculdade de Engenharia, Arquitetura e Urbanismo; Patire Junior, H. [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Div. de Mecanica Espacial e Controle; The high-power microwave sources group

    2003-12-01

    This paper describes the general characteristics of spherical tokamaks, or spherical tori, with a brief overview of work in this area already performed or in progress at several institutions worldwide. The paper presents also the steps in the development of the ETE (Experimento Tokamak Esferico) project, its research program, technical characteristics and operating conditions as of December, 2002 at the Associated Plasma Laboratory (LAP) of the National Space Research Institute (INPE) in Brazil. (author)

  11. Spherical tokamak development in Brazil

    International Nuclear Information System (INIS)

    Ludwig, Gerson Otto; Bosco, Edson Del; Ferreira, Julio Guimaraes

    2003-01-01

    The general characteristics of spherical tokamaks, or spherical tori, with a brief view of work in this area already performed or in progress at several institutions worldwide are described. The paper presents also the steps in the development of the ETE (Experiment Tokamak spheric) project, its research program, technical characteristics and operating conditions as of December, 2002 a the Associated Plasma Laboratory (LAP) of the National Space Research Institute (INPE) in Brazil. (author)

  12. Plasma-Column Equilibrium in Tokamak-5; L'Equilibre d'une Colonne de Plasma dans l'Installation Tokamak-5; Issledovanie ravnovesiya plazmennogo shnura na ustanovke Tokamak-5; El Equilibrio de una Columna de Plasma en la Instalacion 'Tokamak-5'

    Energy Technology Data Exchange (ETDEWEB)

    Muhovatov, V. S. [Institut Atomnoj Ehnergii, Im. I.V. Kurchatova, Moskva, SSSR (Russian Federation)

    1966-04-15

    concordaient qualitativement avec la theorie selon laquelle la colonne de plasma est maintenue en equilibre par l'enveloppe de cuivre. Ils ont egalement etabli que la moyenne de la conductivite electrique du plasma, sur la section de la colonne, atteignait sa valeur maximale lorsque la colonne est disposee de facon concentrique par rapport a l'ouverture du diaphragme, grace au champ transversal B{sub z}. L'auteur montre que pour la plupart des regimes de decharge il existe une bonne concordance quantitative entre les donnees experimentales et la theorie concernant l'equilibre de la colonne a l'interieur de l'enveloppe conductrice. Cependant, pour plusieurs regimes de decharge (faible pression initiale du gaz et fort deplacement {Delta}{sub B} = b{sup 2}B{sub z}c/2J vers la paroi interieure du tore), il a observe une certaine divergence entre la theorie et l'experience. Il a essaye d'evaluer dans quelle mesure le mecanisme de fermeture du circuit des courants de derive au moyen du diaphragme conducteur pouvait contribuer a maintenir l'equilibre de la colonne dans l'installation Tokamak. A cet effet, le diaphragme a ete divise en six segments isoles l'un de l'autre. Au cours de decharges a B{sub z} = 0, on a observe entre les segments superieurs et inferieurs une tension polarisee, depassant de pres d'un ordre de grandeur la temperature des electrons, calculee d'apres la conductivite electrique moyenne du plasma. Pour la valeur optimum de B{sub z}, la tension etait proche de zero; si l'on continuait d'augmenter B{sub z}, elle changeait de signe. L'auteur a egalement observe une dependance analogue de B{sub z} pour les courants passant entre les segments lorsqu'ils etaient connectes par une faible resistance. L'interconnexion de tous les segments n'a pas sensiblement modifie la grandeur du deplacement de la colonne ni les autres caracteristiques de la decharge. Le courant mesure entre les segments est insuffisant pour expliquer la divergence susmentionnee, d'autant plus qu'on l

  13. Bibliography of fusion product physics in tokamaks

    International Nuclear Information System (INIS)

    Hively, L.M.; Sigmar, D.J.

    1989-09-01

    Almost 700 citations have been compiled as the first step in reviewing the recent research on tokamak fusion product effects in tokamaks. The publications are listed alphabetically by the last name of the first author and by subject category

  14. The effect of charge exchange with neutral deuterium on carbon emission in JET divertor plasmas

    International Nuclear Information System (INIS)

    Maggi, C.; Horton, L.; Summers, H.

    1999-11-01

    High density, low temperature divertor plasma operation in tokamaks results in large neutral deuterium concentrations in the divertor volume. In these conditions, low energy charge transfer reactions between neutral deuterium and the impurity ions can in principle enhance the impurity radiative losses and thus help to reduce the maximum heat load to the divertor target. A quantitative study of the effect of charge exchange on carbon emission is presented, applied to the JET divertor. Total and state selective effective charge exchange recombination rate coefficients were calculated in the collisional radiative picture. These coefficients were coupled to divertor and impurity transport models to study the effect of charge exchange on the measured carbon spectral emission in JET divertor discharges. The sensitivity of the effect of charge exchange to the assumptions in the impurity transport model was also investigated. A reassessment was made of fundamental charge exchange cross section data in support of this study. (author)

  15. The scientific case for a JET D-T experiment

    International Nuclear Information System (INIS)

    Weisen, H.; Sips, A. C. C.; Horton, L. D.; Challis, C. D.; Sharapov, S. E.; Zastrow, K.-D.; Eriksson, L.-G.; Batistoni, P.

    2014-01-01

    After the first high power D-T experiment in JET in 1997 (DTE1), when JET was equipped with Carbon PFC's, a proposed second high power (up to ∼40MW) D-T campaign (DTE2) in the current Be/W vessel will address essential operational, technical, diagnostics and scientific issues in support of ITER. These experiments are proposed to minimize the risks to ITER by testing strategies for the management of the in-vessel tritium content, by providing the basis for transferring operational scenarios from non-active operation to D-T mixtures and by addressing the issue of the neutron measurement accuracy. Dedicated campaigns with operation in Deuterium, Hydrogen and Tritium before the D-T campaign proper will allow the investigation of isotope scaling of the H-mode transition, pedestal physics, heat, particle, momentum and impurity transport in much greater detail than was possible in DTE1. The D-T campaign proper will include validations of the baseline ELMy H-Mode scenario, of the hybrid H-mode and advanced tokamak scenarios, as well as the investigation of alpha particle physics and the qualification of ICRH scenarios suitable for D-T operation. This paper reviews the scientific goals of DTE2 together with a summary of the results of DTE1

  16. Tokamak startup: problems and scenarios related to the transient phases of ignited tokamak operations

    International Nuclear Information System (INIS)

    Sheffield, J.

    1985-01-01

    During recent years improvements have been made to tokamak startup procedures, which are important to the optimization of ignited tokamaks. The use of rf-assisted startup and noninductive current drive has led to substantial reduction and even complete elimination of the volt-seconds used during startup, relaxing constraints on poloidal coil, vacuum vessel, and structure design. This paper reviews these and other improvements and discusses the various bulk heating techniques that may be used to ignite a D-T plasma

  17. Edge pedestal characteristics in JET and JT-60U tokamaks under variable toroidal field ripple

    NARCIS (Netherlands)

    Urano, H.; Saibene, G.; Oyama, N.; Parail, V.; P. de Vries,; Sartori, R.; Kamada, Y.; Kamiya, K.; Loarte, A.; Lonnroth, J.; Sakamoto, Y.; Salmi, A.; Shinohara, K.; Takenaga, H.; Yoshida, M.

    2011-01-01

    The effects of toroidal field (TF) ripple on the edge pedestal characteristics were examined in the TF ripple scan experiments at the plasma current I(p) of 1.1 MA in JET and JT-60U. The TF ripple amplitude delta(R) was defined as a value averaged over the existing ripple wells at the separatrix on

  18. Determination of the Jet Neutron Rate and Fusion Power using the Magnetic Proton Recoil Neutron Spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Sjoestrand, Henrik

    2003-01-01

    In this thesis a new independent method has been developed to enable precise measurements of neutron yields and rates from fusion plasmas and thereby determining the fusion power and fusion energy. The new method, together with the associated diagnostics, can provide information of great importance to present and future high fusion yield experiments, such as the Joint European Torus (JET) tokamak and the International Thermonuclear Experiment Reactor (ITER). The method has been applied to data from high fusion rate experiments from the tritium campaign at JET. By using the count-rate from the Magnetic Proton Recoil (MPR) neutron spectrometer the number of neutrons in the spectrometer's line of sight has been calculated. To be able to do this, all relevant factors between the plasma and the instrument have been evaluated. The number of neutrons in the MPR line of sight has been related to the total number of produced neutrons in the plasma by using information on the neutron emission profile. The achieved results have been compared with other JET neutron diagnostic data and the agreement is shown to be very good.

  19. MAST: a Mega Amp Spherical Tokamak

    International Nuclear Information System (INIS)

    Darke, A.C.; Harbar, J.R.; Hay, J.H.; Hicks, J.B.; Hill, J.W.; McKenzie, J.S.; Morris, A.W.; Nightingale, M.P.S.; Todd, T.N.; Voss, G.M.; Watkins, J.R.

    1995-01-01

    The highly successful tight aspect ratio tokamak research pioneered on the START machine at Culham, together with the attractive possibilities of the concept, suggest a larger device should be considered. The design of a Mega Amp Spherical Tokamak is described, operating at much higher currents and over longer pulses than START and compatible with strong additional heating. (orig.)

  20. The ARIES-I tokamak reactor study

    International Nuclear Information System (INIS)

    1991-01-01

    This report contains an overview of the Aries-I tokamak reactor study. The following topics are discussed on this tokamak: Systems studies; equilibrium, stability, and transport; summary and conclusions; current drive; impurity control system; tritium systems; magnet engineering; fusion-power-core engineering; power conversion; Aries-I safety design and analysis; design layout and maintenance; and start-up and operations

  1. Economic evaluation of tokamak power plants

    International Nuclear Information System (INIS)

    Reid, R.L.; Steiner, D.

    1977-01-01

    This study reports the impact of plasma operating characteristics, engineering options, and technology on the capital cost trends of tokamak power plants. Tokamak power systems are compared to other advanced energy systems and found to be economically competitive. A three-phase strategy for demonstrating commercial feasibility of fusion power, based on a common-site multiple-unit concept, is presented

  2. Development of LEAP-JET code for sodium-water reaction analysis. Validation by sodium-water reaction tests (SWAT-1R)

    International Nuclear Information System (INIS)

    Seino, Hiroshi; Hamada, Hirotsugu

    2004-03-01

    The sodium-water reaction event in an FBR steam generator (SG) has influence on the safety, economical efficiency, etc. of the plant, so that the selection of design base leak (DBL) of the SG is considered as one of the important matters. The clarification of the sodium-water reaction phenomenon and the development of an analysis model are necessary to estimate the sodium-water reaction event with high accuracy and rationality in selecting the DBL. The reaction jet model is pointed out as a part of the necessary improvements to evaluate the overheating tube rupture of large SGs, since the behavior of overheating tube rupture is largely affected by the reaction jet conditions outside the tube. Therefore, LEAP-JET has been developed as an analysis code for the simulation of sodium-water reactions. This document shows the validation of the LEAP-JET code by the Sodium-Water Reaction Test (SWAT-1R). The following results have been obtained: (1) The reaction rate constant, K, is estimated at between 0.001≤K≤0.1 from the LEAP-JET analysis of the SWAT-1R data. (2) The analytical results on the high-temperature region and the behaviors of reaction consumption (Na, H 2 O) and products (H 2 , NaOH, Na 2 O) are considered to be physically reasonable. (3) The LEAP-JET analysis shows the tendency of overestimation in the maximum temperature and temperature distribution of the reaction jet. (4) In the LEAP-JET analysis, the numerical calculation becomes unstably, especially in the mesh containing quite small sodium mass. Therefore, it is necessary to modify the computational algorism to stabilize it and obtain the optimum value of K in sodium-water reactions. (author)

  3. Tokamaks: from A D Sakharov to the present (the 60-year history of tokamaks)

    International Nuclear Information System (INIS)

    Azizov, E A

    2012-01-01

    The paper is prepared on the basis of the report presented at the session of the Physical Sciences Division of the Russian Academy of Sciences (RAS) at the Lebedev Physical Institute, RAS on 25 May 2011, devoted to the 90-year jubilee of Academician Andrei D Sakharov - the initiator of controlled nuclear fusion research in the USSR. The 60-year history of plasma research work in toroidal devices with a longitudinal magnetic field suggested by Andrei D Sakharov and Igor E Tamm in 1950 for the confinement of fusion plasma and known at present as tokamaks is described in brief. The recent (2006) agreement among Russia, the EU, the USA, Japan, China, the Republic of Korea, and India on the joint construction of the international thermonuclear experimental reactor (ITER) in France based on the tokamak concept is discussed. Prospects for using the tokamak as a thermonuclear (14 MeV) neutron source are examined. (conferences and symposia)

  4. Mitigation of divertor heat loads by strike point sweeping in high power JET discharges

    Science.gov (United States)

    Silburn, S. A.; Matthews, G. F.; Challis, C. D.; Frigione, D.; Graves, J. P.; Mantsinen, M. J.; Belonohy, E.; Hobirk, J.; Iglesias, D.; Keeling, D. L.; King, D.; Kirov, K.; Lennholm, M.; Lomas, P. J.; Moradi, S.; Sips, A. C. C.; Tsalas, M.; Contributors, JET

    2017-12-01

    Deliberate periodic movement (sweeping) of the high heat flux divertor strike lines in tokamak plasmas can be used to manage the heat fluxes experienced by exhaust handling plasma facing components, by spreading the heat loads over a larger surface area. Sweeping has recently been adopted as a routine part of the main high performance plasma configurations used on JET, and has enabled pulses with 30 MW plasma heating power and 10 MW radiation to run for 5 s without overheating the divertor tiles. We present analysis of the effectiveness of sweeping for divertor temperature control on JET, using infrared camera data and comparison with a simple 2D heat diffusion model. Around 50% reduction in tile temperature rise is obtained with 5.4 cm sweeping compared to the un-swept case, and the temperature reduction is found to scale slower than linearly with sweeping amplitude in both experiments and modelling. Compatibility of sweeping with high fusion performance is demonstrated, and effects of sweeping on the edge-localised mode behaviour of the plasma are reported and discussed. The prospects of using sweeping in future JET experiments with up to 40 MW heating power are investigated using a model validated against existing experimental data.

  5. Mitigation of divertor heat loads by strike point sweeping in high power JET discharges

    International Nuclear Information System (INIS)

    Silburn, S A; Matthews, G F; Challis, C D; Belonohy, E; Iglesias, D; Keeling, D L; King, D; Kirov, K; Lomas, P J; Frigione, D; Graves, J P; Mantsinen, M J; Hobirk, J; Lennholm, M; Moradi, S; Sips, A C C; Tsalas, M

    2017-01-01

    Deliberate periodic movement (sweeping) of the high heat flux divertor strike lines in tokamak plasmas can be used to manage the heat fluxes experienced by exhaust handling plasma facing components, by spreading the heat loads over a larger surface area. Sweeping has recently been adopted as a routine part of the main high performance plasma configurations used on JET, and has enabled pulses with 30 MW plasma heating power and 10 MW radiation to run for 5 s without overheating the divertor tiles. We present analysis of the effectiveness of sweeping for divertor temperature control on JET, using infrared camera data and comparison with a simple 2D heat diffusion model. Around 50% reduction in tile temperature rise is obtained with 5.4 cm sweeping compared to the un-swept case, and the temperature reduction is found to scale slower than linearly with sweeping amplitude in both experiments and modelling. Compatibility of sweeping with high fusion performance is demonstrated, and effects of sweeping on the edge-localised mode behaviour of the plasma are reported and discussed. The prospects of using sweeping in future JET experiments with up to 40 MW heating power are investigated using a model validated against existing experimental data. (paper)

  6. Plea for stellarator funding raps tokamaks

    International Nuclear Information System (INIS)

    Blake, M.

    1992-01-01

    The funding crunch in magnetic confinement fusion development has moved the editor of a largely technical publication to speak out on a policy issue. James A. Rome, who edits Stellarator News from the Fusion Energy Division at Oak Ridge National Laboratory, wrote an editorial that appeared on the front page of the May 1992 issue. It was titled open-quotes The US Stellarator Program: A Time for Renewal,close quotes and while it focused chiefly on that subject (and lamented the lack of funding for the operation of the existing ATF stellarator at Oak Ridge), it also cited some of the problems inherent in the mainline MCF approach--the tokamak--and stated that if the money can be found for further tokamak design upgrades, it should also be found for stellarators. Rome wrote, open-quotes There is growing recognition in the US, and elsewhere, that the conventional tokamak does not extrapolate to a commercially competitive energy source except with very high field coils ( 1000 MWe).close quotes He pointed up open-quotes the difficulty of simultaneously satisfying conflicting tokamak requirements for efficient current drive, high bootstrap-current fraction, complete avoidance of disruptions, adequate beta limits, and edge-plasma properties compatible with improved (H-mode) confinement and acceptable erosion of divertor plates.close quotes He then called for support for the stellarator as open-quotes the only concept that has performance comparable to that achieved in tokamaks without the plasma-current-related limitations listed above.close quotes

  7. Electron thermal transport in tokamak plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Konings, J A

    1994-11-30

    The process of fusion of small nuclei thereby releasing energy, as it occurs continuously in the sun, is essential for the existence of mankind. The same process applied in a controlled way on earth would provide a clean and an abundant energy source, and be the long term solution of the energy problem. Nuclear fusion requires an extremely hot (10{sup 8} K) ionized gas, a plasma, that can only be maintained if it is kept insulated from any material wall. In the so called `tokamak` this is achieved by using magnetic fields. The termal insulation, which is essential if one wants to keep the plasma at the high `fusion` temperature, can be predicted using basic plasma therory. A comparison with experiments in tokamaks, however, showed that the electron enery losses are ten to hundred times larger than this theory predicts. This `anomalous transport` of thermal energy implies that, to reach the condition for nuclear fusion, a fusion reactor must have very large dimensions. This may put the economic feasibility of fusion power in jeopardy. Therefore, in a worldwide collaboration, physicists study tokamak plasmas in an attempt to understand and control the energy losses. From a scientific point of view, the mechanisms driving anomalous transport are one of the challenges in fudamental plasma physics. In Nieuwegein, a tokamak experiment (the Rijnhuizen Tokamak Project, RTP) is dedicated to the study of anomalous transport, in an international collaboration with other laboratories. (orig./WL).

  8. Digital controlled pulsed electric system of the ETE tokamak. First report; Sistema eletrico pulsado com controle digital do Tokamak ETE (experimento Tokamak esferico). Primeiro relatorio

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, Luis Felipe de F.P.W.; Del Bosco, Edson

    1997-12-31

    This reports presents a summary on the thermonuclear fusion and application for energy supply purposes. The tokamak device operation and the magnetic field production systems are described. The ETE tokamak is a small aspect ratio device designed for plasma physics and thermonuclear fusion studies, which presently is under construction at the Laboratorio Associado de Plasma (LAP), Instituto Nacional de Pesquisas Espaciais (INPE) - S.J. dos Campos - S. Paulo. (author) 55 refs., 40 figs.

  9. Digital controlled pulsed electric system of the ETE tokamak. First report; Sistema eletrico pulsado com controle digital do Tokamak ETE (experimento Tokamak esferico). Primeiro relatorio

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, Luis Felipe de F.P.W.; Del Bosco, Edson

    1998-12-31

    This reports presents a summary on the thermonuclear fusion and application for energy supply purposes. The tokamak device operation and the magnetic field production systems are described. The ETE tokamak is a small aspect ratio device designed for plasma physics and thermonuclear fusion studies, which presently is under construction at the Laboratorio Associado de Plasma (LAP), Instituto Nacional de Pesquisas Espaciais (INPE) - S.J. dos Campos - S. Paulo. (author) 55 refs., 40 figs.

  10. Analysis of tokamak plasma confinement modes using the fast

    Indian Academy of Sciences (India)

    The Fourier analysis is a satisfactory technique for detecting plasma confinement modes in tokamaks. The confinement mode of tokamak plasma was analysed using the fast Fourier transformation (FFT). For this purpose, we used the data of Mirnov coils that is one of the identifying tools in the IR-T1 tokamak, with and ...

  11. Empirical scaling for present Ohmically heated tokamaks

    International Nuclear Information System (INIS)

    Daughney, C.

    1975-01-01

    Experimental results from the Adiabatic Toroidal Compressor (ATC) tokamak are used to obtain empirical scaling laws for the average electron temperature and electron energy confinement time as functions of the average electron density, the effective ion charge, and the plasma current. These scaling laws are extended to include dependence upon minor and major plasma radius and toroidal field strength through a comparison of the various tokamaks described in the literature. Electron thermal conductivity is the dominant loss process for the ATC tokamak. The parametric dependences of the observed electron thermal conductivity are not explained by present theoretical considerations. The electron temperature obtained with Ohmic heating is shown to be a function of current density - which will not be increased in the next generation of large tokamaks. However, the temperature dependence of the electron energy confinement time suggests that significant improvement in confinement time will be obtained with supplementary electron heating. (author)

  12. Development of a novel fast frequency modulation scheme for the JET multi-channel reflectometer

    International Nuclear Information System (INIS)

    Deliyanakis, N.

    1999-10-01

    A novel frequency modulation scheme has been developed for the multi-channel reflectometer used to measure density profiles and density fluctuations on the JET tokamak. This reflectometer normally uses slow frequency sweeping, combined with fixed-frequency operation, to measure the group delay, as well as plasma fluctuations, at 10 different microwave frequencies. The novel scheme uses continuous frequency modulation on a time-scale much faster than that of plasma fluctuations, the main aim being to make the group delay measurement more robust against plasma fluctuations. This paper discusses the theoretical background of the scheme, gives a detailed description of the system, and presents results from plasma measurements. (author)

  13. Plasma biasing by fast particles generation in front of CASTOR and TORE SUPRA tokamak LH grills

    International Nuclear Information System (INIS)

    Petrzilka, V.; Jakubka, K.; Klima, R.

    1999-01-01

    Computation results are presented concerning the electron acceleration by the LH wave alone, which are necessary for determining the value of the effective ponderomotive potential W. One set of selected parameters is representative for large tokamaks like Tore Supra and JET; the other set is representative for the small CASTOR tokamak. To estimate the value of W, the test-particle model was used for describing the electron acceleration. Then, by using the two-fluid model, profiles of U and Ε z are presented. Further, by using the corresponding value of W in the Particle-in-Cell model for the simulations of the plasma vortex in front of the LH grill, the effects are explored of the electrostatic fields Ε r , Ε θ and Ε z , on the following processes: 1. particle acceleration in front of LH grills by rf waves - it is demonstrated that in addition to electron acceleration, the charge-separation electrostatic field Ε z also accelerates ions to energies of several keV; 2. effects of plasma sources on the flow of particles from the narrow layer in front of the LH grill mouth - here it is shown that ionization alone is not sufficient for creating the experimentally observed plasma densities in front of LH grills

  14. Simulation of a major tokamak disruption

    International Nuclear Information System (INIS)

    White, R.B.; Monticello, D.A.; Rosenbluth, M.N.

    1977-08-01

    It is known that the internal tokamak disruption leads to a current profile which is flattened inside the surface where the safety factor equals unity. It is shown that such a profile can lead to m = 2 magnetic islands which grow to fill a substantial part of the tokamak cross section in a time consistent with the observations of the major disruption

  15. Edge plasma diagnostics on Tore Supra tokamak

    International Nuclear Information System (INIS)

    Fujita, Junji

    1991-01-01

    From 1988 to 1991, the international scientific research 'Diagnosis of peripheral plasma in Tore Supra tokamak' was carried out as a three-year plan receiving the support of the scientific research expense of the Ministry of Education. This is to apply the method of measuring electron density distribution by neutral lithium beam probe spectroscopy to the measurement of the electron density distribution in the peripheral plasma in Tore Supra Tokamak in France. Among many tokamaks in operation doing respective characteristics researches, the Tore Supra generates the toroidal magnetic field by using superconducting coils, and aims at the long time discharge for 30 sec. for the time being, and for 300 sec. in future. In the plasma generators for long time discharge like this, the technology of particle control is a large problem. For this purpose, a divertor was added to the Tore Supra. In order to advance the research on particle control, it is necessary to examine the behavior of plasma in the peripheral part in detail. The measurement of peripheral plasma in tokamaks, beam probe spectroscopy, the Tore Supra tokamak, the progress of the joint research, the problems in the joint research and the perspective of hereafter are reported. (K.I.)

  16. Integral torque balance in tokamaks

    International Nuclear Information System (INIS)

    Pustovitov, V.D.

    2011-01-01

    The study is aimed at clarifying the balance between the sinks and sources in the problem of intrinsic plasma rotation in tokamaks reviewed recently by deGrassie (2009 Plasma Phys. Control. Fusion 51 124047). The integral torque on the toroidal plasma is calculated analytically using the most general magnetohydrodynamic (MHD) plasma model taking account of plasma anisotropy and viscosity. The contributions due to several mechanisms are separated and compared. It is shown that some of them, though, possibly, important in establishing the rotation velocity profile in the plasma, may give small input into the integral torque, but an important contribution can come from the magnetic field breaking the axial symmetry of the configuration. In tokamaks, this can be the error field, the toroidal field ripple or the magnetic perturbation created by the correction coils in the dedicated experiments. The estimates for the error-field-induced electromagnetic torque show that the amplitude of this torque is comparable to the typical values of torques introduced into the plasma by neutral beam injection. The obtained relations allow us to quantify the effect that can be produced by the existing correction coils in tokamaks on the plasma rotation, which can be used in experiments to study the origin and physics of intrinsic rotation in tokamaks. Several problems are proposed for theoretical studies and experimental tests.

  17. Tokamak and RFP ignition requirements

    International Nuclear Information System (INIS)

    Werley, K.A.

    1991-01-01

    A plasma model is applied to calculate numerically transport- confinement (nτ E ) requirements and steady-state operation tokamak. The CIT tokamak and RFP ignition conditions are examined. Physics differences between RFP and tokamaks, and their consequences for a DT ignition machine, are discussed. The ignition RFP, compared to a tokamak, has many physics advantages, including ohmic heating to ignition (no need for auxiliary heating systems), higher beta, low ignition current, less sensitivity of ignition requirements to impurity effects, no hard disruptions (associated with beta or density limits), and successful operation with high radiation fractions (f RAD ∼ 0.95). These physics advantages, coupled with important engineering advantages associated with lower external magnetic fields, larger aspect ratios, and smaller plasma cross sections translate into significant cost reductions for both ignition and power reactor. The primary drawback of the RFP is the uncertainty that the present confinement scaling will extrapolate to reactor regimes. The 4-MA ZTH was expected to extend the nτ E transport scaling data three order of magnitude above ZT-40M results, and if the present scaling held, to achieve a DT-equivalent scientific energy breakeven, Q=1. A basecase RFP ignition point is identified with a plasma current of 8.1 MA and no auxiliary heating. 16 refs., 4 figs., 1 tab

  18. Physics design of an ultra-long pulsed tokamak reactor

    International Nuclear Information System (INIS)

    Ogawa, Y.; Inoue, N.; Wang, J.; Yamamoto, T.; Okano, K.

    1993-01-01

    A pulsed tokamak reactor driven only by inductive current drive has recently revived, because the non-inductive current drive efficiency seems to be too low to realize a steady-state tokamak reactor with sufficiently high energy gain Q. Essential problems in pulsed operation mode is considered to be material fatigue due to cyclic operation and expensive energy storage system to keep continuous electric output during a dwell time. To overcome these problems, we have proposed an ultra-long pulsed tokamak reactor called IDLT (abbr. Inductively operated Day-Long Tokamak), which has the major and minor radii of 10 m and 1.87 m, respectively, sufficiently to ensure the burning period of about ten hours. Here we discuss physical features of inductively operated tokamak plasmas, employing the similar constraints with ITER CDA design for engineering issues. (author) 9 refs., 2 figs., 1 tab

  19. System assessment of helical reactors in comparison with tokamaks

    International Nuclear Information System (INIS)

    Yamazaki, K.; Imagawa, S.; Muroga, T.; Sagara, A.; Okamura, S.

    2002-10-01

    A comparative assessment of tokamak and helical reactors has been performed using equivalent physics/engineering model and common costing model. Higher-temperature plasma operation is required in tokamak reactors to increase bootstrap current fraction and to reduce current-drive (CD) power. In helical systems, lower-temperature operation is feasible and desirable to reduce helical ripple transport. The capital cost of helical reactor is rather high, however, the cost of electricity (COE) is almost same as that of tokamak reactor because of smaller re-circulation power (no CD power) and less-frequent blanket replacement (lower neutron wall loading). The standard LHD-type helical reactor with 5% beta value is economically equivalent to the standard tokamak with 3% beta. The COE of lower-aspect ratio helical reactor is on the same level of high-β N tokamak reactors. (author)

  20. Jet mass spectra in Higgs+one jet at NNLL

    International Nuclear Information System (INIS)

    Jouttenus, Teppo T.; Stewart, Iain W.; Waalewijn, Wouter J.

    2013-02-01

    The invariant mass of a jet is a benchmark variable describing the structure of jets at the LHC. We calculate the jet mass spectrum for Higgs plus one jet at the LHC at next-to-next-to-leading logarithmic (NNLL) order using a factorization formula. At this order, the cross section becomes sensitive to perturbation theory at the soft m 2 jet /p jet T scale. Our calculation is exclusive and uses the 1-jettiness global event shape to implement a veto on additional jets. The dominant dependence on the jet veto is removed by normalizing the spectrum, leaving residual dependence from non-global logarithms depending on the ratio of the jet mass and jet veto variables. For our exclusive jet cross section these non-global logarithms are parametrically smaller than in the inclusive case, allowing us to obtain a complete NNLL result. Results for the dependence of the jet mass spectrum on the kinematics, jet algorithm, and jet size R are given. Using individual partonic channels we illustrate the difference between the jet mass spectra for quark and gluon jets. We also study the effect of hadronization and underlying event on the jet mass in Pythia. To highlight the similarity of inclusive and exclusive jet mass spectra, a comparison to LHC data is presented.

  1. Magnetic field structure of experimental high beta tokamak equilibria

    International Nuclear Information System (INIS)

    Deniz, A.V.

    1986-01-01

    The magnetic field structure of several low and high β tokamaks in the Columbia High Beta Tokamak (HBT) was determined by high-impedance internal magnetic probes. From the measurement of the magnetic field, the poloidal flux, toroidal flux, toroidal current, and safety factor are calculated. In addition, the plasma position and cross-sectional shape are determined. The extent of the perturbation of the plasma by the probe was investigated and was found to be acceptably small. The tokamaks have major radii of approx.0.24 m, minor radii of approx.0.05 m, toroidal plasma current densities of approx.10 6 A/m 2 , and line-integrated electron densities of approx.10 20 m -2 . The major difference between the low and high β tokamaks is that the high β tokamak was observed to have an outward shift in major radius of both the magnetic center and peak of the toroidal current density. The magnetic center moves inward in major radius after 20 to 30 μsec, presumably because the plasma maintains major radial equilibrium as its pressure decreases from radiation due to impurity atoms. Both the equilibrium and the production of these tokamaks from a toroidal field stabilized z-pinch are modeled computationally. One tokamak evolves from a state with low β features, through a possibly unstable state, to a state with high β features

  2. Resistive toroidal stability of internal kink modes in circular and shaped tokamaks

    International Nuclear Information System (INIS)

    Bondeson, A.; Luetjens, H.; Vlad, G.

    1991-12-01

    The linear resistive magnetohydrodynamical (MHD) stability of the n=1 internal kink mode in tokamaks is studied by toroidal computations. The stabilizing influence of small aspect ratio is confirmed, but it is found that shaping of the cross section influences the internal kink mode significantly. For finite pressure and small resistivity, curvature effects at the q=1 surface make the stability sensitively dependent on shape, and ellipticity (including JET shape) is destabilizing. Only a very restricted set of finite pressure equilibria is completely stable for q 0 <1. A typical result is that the resistive kink mode is slowed down by toroidal effects to a weak tearing/resistive interchange mode. It is suggested that weak resistive instabilities are stabilized during the ramp phase of the sawteeth by effects not included in the linear resistive MHD model. Possible mechanisms for triggering a sawtooth crash are discussed. (author) 18 figs., 34 refs

  3. Jet angularity measurements for single inclusive jet production

    Science.gov (United States)

    Kang, Zhong-Bo; Lee, Kyle; Ringer, Felix

    2018-04-01

    We study jet angularity measurements for single-inclusive jet production at the LHC. Jet angularities depend on a continuous parameter a allowing for a smooth interpolation between different traditional jet shape observables. We establish a factorization theorem within Soft Collinear Effective Theory (SCET) where we consistently take into account in- and out-of-jet radiation by making use of semi-inclusive jet functions. For comparison, we elaborate on the differences to jet angularities measured on an exclusive jet sample. All the necessary ingredients for the resummation at next-to-leading logarithmic (NLL) accuracy are presented within the effective field theory framework. We expect semiinclusive jet angularity measurements to be feasible at the LHC and we present theoretical predictions for the relevant kinematic range. In addition, we investigate the potential impact of jet angularities for quark-gluon discrimination.

  4. INTEGRATED PLASMA CONTROL FOR ADVANCED TOKAMAKS

    International Nuclear Information System (INIS)

    HUMPHREYS, D.A.; FERRON, J.R.; JOHNSON, R.D; LEUER, J.A.; PENAFLOR, B.G.; WALKER, M.L.; WELANDER, A.S.; KHAYRUTDINOV, R.R; DOKOUKA, V.; EDGELL, D.H.; FRANSSON, C.M.

    2004-03-01

    OAK-B135 Advanced tokamaks (AT) are distinguished from conventional tokamaks by their high degree of shaping, achievement of profiles optimized for high confinement and stability characteristics, and active stabilization of MHD instabilities to attain high values of normalized beta and confinement. These high performance fusion devices thus require accurate regulation of the plasma boundary, internal profiles, pumping, fueling, and heating, as well as simultaneous and well-coordinated MHD control action to stabilize such instabilities as tearing modes and resistive wall modes. Satisfying the simultaneous demands on control accuracy, reliability, and performance for all of these subsystems requires a high degree of integration in both design and operation of the plasma control system in an advanced tokamak. The present work describes the approach, benefits, and progress made in integrated plasma control with application examples drawn from the DIII-D tokamak. The approach includes construction of plasma and system response models, validation of models against operating experiments, design of integrated controllers which operate in concert with one another as well as with supervisory modules, simulation of control action against off-line and actual machine control platforms, and iteration of the design-test loop to optimize performance

  5. Jet mass spectra in Higgs+one jet at NNLL

    Energy Technology Data Exchange (ETDEWEB)

    Jouttenus, Teppo T.; Stewart, Iain W. [Massachusetts Institute of Technology, Cambridge, MA (United States). Center for Theoretical Physics; Tackmann, Frank J. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Waalewijn, Wouter J. [California Univ., San Diego, La Jolla, CA (United States). Dept. of Physics

    2013-02-15

    The invariant mass of a jet is a benchmark variable describing the structure of jets at the LHC. We calculate the jet mass spectrum for Higgs plus one jet at the LHC at next-to-next-to-leading logarithmic (NNLL) order using a factorization formula. At this order, the cross section becomes sensitive to perturbation theory at the soft m{sup 2}{sub jet}/p{sup jet}{sub T} scale. Our calculation is exclusive and uses the 1-jettiness global event shape to implement a veto on additional jets. The dominant dependence on the jet veto is removed by normalizing the spectrum, leaving residual dependence from non-global logarithms depending on the ratio of the jet mass and jet veto variables. For our exclusive jet cross section these non-global logarithms are parametrically smaller than in the inclusive case, allowing us to obtain a complete NNLL result. Results for the dependence of the jet mass spectrum on the kinematics, jet algorithm, and jet size R are given. Using individual partonic channels we illustrate the difference between the jet mass spectra for quark and gluon jets. We also study the effect of hadronization and underlying event on the jet mass in Pythia. To highlight the similarity of inclusive and exclusive jet mass spectra, a comparison to LHC data is presented.

  6. ARIES tokamak reactor study

    International Nuclear Information System (INIS)

    Steiner, D.; Embrechts, M.

    1990-07-01

    This is a status report on technical progress relative to the tasks identified for the fifth year of Grant No. FG02-85-ER52118. The ARIES tokamak reactor study is a multi-institutional effort to develop several visions of the tokamak as an attractive fusion reactor with enhanced economic, safety, and environmental features. The ARIES study is being coordinated by UCLA and involves a number of institutions, including RPI. The RPI group has been pursuing the following areas of research in the context of the ARIES-I design effort: MHD equilibrium and stability analyses; plasma-edge modeling and blanket materials issues. Progress in these areas is summarized herein

  7. The JET project (design proposal)

    International Nuclear Information System (INIS)

    1976-03-01

    This proposal describes a large Tokamak experiment, which aims to study plasma behavior in conditions and dimensions approaching those required in a fusion reactor. The maximum plasma minor radius (a) is 1.25m and the major radius (R 0 ) is 2.96m. An important feature is the flexibility to study, for plasma currents in the 1→3MA range, a wide range of aspect ratios (R 0 /a=2.37→5), toroidal magnetic fields (up to 3.6T), minor radii (0.6→1.25m) and elongation ratios (b/a=1→3.5). The cost of the apparatus, power supplies, plasma heating equipment and specific diagnostics is estimated as 70.1Muc (march 1975 prices, 1uc=50FB). The total construction phase cost including commissioning, buildings and staff is 135Muc. These figures include an average overall contingency of 30%. The construction time for the project is estimated at 5 years and requires 370 professional man years of effort in the construction organisation with additional effort deployed by the Associated Laboratories in such areas as diagnostics and plasma heating. This design proposal is arranged as follows: an introduction to the field of fusion research is given and relates JET to the European and international programmes; a concise summary of the design proposal describes the objectives of research with JET, and gives a brief description of the apparatus, the cost and construction schedules, the proposed experimental programme and the possible modes of operation of the device. A detailed account of the engineering design and the staff and cost estimates is presented

  8. Improvement of tokamak performance by injection of electrons

    International Nuclear Information System (INIS)

    Ono, Masayuki.

    1992-12-01

    Concepts for improving tokamak performance by utilizing injection of hot electrons are discussed. Motivation of this paper is to introduce the research work being performed in this area and to refer the interested readers to the literature for more detail. The electron injection based concepts presented here have been developed in the CDX, CCT, and CDX-U tokamak facilities. The following three promising application areas of electron injection are described here: 1. Non-inductive current drive, 2. Plasma preionization for tokamak start-up assist, and 3. Charging-up of tokamak flux surfaces for improved plasma confinement. The main motivation for the dc-helicity injection current drive is in its efficiency that, in theory, is independent of plasma density. This property makes it attractive for driving currents in high density reactor plasmas

  9. Neutronic analysis of fusion tokamak devices by PHITS

    International Nuclear Information System (INIS)

    Sukegawa, Atsuhiko M.; Takiyoshi, Kouji; Amano, Toshio; Kawasaki, Hiromitsu; Okuno, Koichi

    2011-01-01

    A complete 3D neutronic analysis by PHITS (Particle and Heavy Ion Transport code System) has been performed for fusion tokamak devices such as JT-60U device and JT-60 Superconducting tokamak device (JT-60 Super Advanced). The mono-energetic neutrons (E n =2.45 MeV) of the DD fusion devices are used for the neutron source in the analysis. The visual neutron flux distribution for the estimation of the port streaming and the dose rate around the fusion tokamak devices has been calculated by the PHITS. The PHITS analysis makes it clear that the effect of the port streaming of superconducting fusion tokamak device with the cryostat is crucial and the calculated neutron spectrum results by PHITS agree with the MCNP-4C2 results. (author)

  10. Multi-mode remote participation on the GOLEM tokamak

    International Nuclear Information System (INIS)

    Svoboda, V.; Huang, B.; Mlynar, J.; Pokol, G.I.; Stoeckel, J.; Vondrasek, G.

    2011-01-01

    The GOLEM tokamak (formerly CASTOR) at Czech Technical University is demonstrated as an educational tokamak device for domestic and foreign students. Remote participation of several foreign universities (in Hungary, Belgium, Poland and Costa Rica) has been successfully performed. A unique feature of the GOLEM device is functionality which enables complete remote participation and control, solely through Internet access. Basic remote control is possible either in online mode via WWW/SSH interface or offline mode using batch processing code. Discharge parameters are set in each case to configure the tokamak for a plasma discharge. Using the X11 protocol it is possible to control in an advanced mode many technological aspects of the tokamak operation, including: i) vacuum pump initialization, ii) chamber baking, iii) charging of power supplies, iv) plasma discharge scenario, v) data acquisition system.

  11. Tokamak Physics Experiment (TPX) power supply design and development

    International Nuclear Information System (INIS)

    Neumeyer, C.; Bronner, G.; Lu, E.; Ramakrishnan, S.

    1995-01-01

    The Tokamak Physics Experiment (TPX) is an advanced tokamak project aimed at the production of quasi-steady state plasmas with advanced shape, heating, and particle control. TPX is to be built at the Princeton Plasma Physics Laboratory (PPPL) using many of the facilities from the Tokamak Fusion Test Reactor (TFTR). TPX will be the first tokamak to utilize superconducting (SC) magnets in both the toroidal field (TF) and poloidal field (PF) systems. This new feature requires a departure from the traditional tokamak power supply schemes. This paper describes the plan for the adaptation of the PPPL/FTR power system facilities to supply TPX. Five major areas are addressed, namely the AC power system, the TF, PF and Fast Plasma Position Control (FPPC) power supplies, and quench protection for the TF and PF systems. Special emphasis is placed on the development of new power supply and protection schemes

  12. High performance operational limits of tokamak and helical systems

    International Nuclear Information System (INIS)

    Yamazaki, Kozo; Kikuchi, Mitsuru

    2003-01-01

    The plasma operational boundaries of tokamak and helical systems are surveyed and compared with each other. Global confinement scaling laws are similar and gyro-Bohm like, however, local transport process is different due to sawtooth oscillations in tokamaks and ripple transport loss in helical systems. As for stability limits, achievable tokamak beta is explained by ideal or resistive MHD theories. On the other hand, beta values obtained so far in helical system are beyond ideal Mercier mode limits. Density limits in tokamak are often related to the coupling between radiation collapse and disruptive MHD instabilities, but the slow radiation collapse is dominant in the helical system. The pulse length of both tokamak and helical systems is on the order of hours in small machines, and the longer-pulsed good-confinement plasma operations compatible with radiative divertors are anticipated in both systems in the future. (author)

  13. Overview of manifold learning techniques for the investigation of disruptions on JET

    International Nuclear Information System (INIS)

    Cannas, B; Fanni, A; Pau, A; Sias, G; Murari, A

    2014-01-01

    Identifying a low-dimensional embedding of a high-dimensional data set allows exploration of the data structure. In this paper we tested some existing manifold learning techniques for discovering such embedding within the multidimensional operational space of a nuclear fusion tokamak. Among the manifold learning methods, the following approaches have been investigated: linear methods, such as principal component analysis and grand tour, and nonlinear methods, such as self-organizing map and its probabilistic variant, generative topographic mapping. In particular, the last two methods allow us to obtain a low-dimensional (typically two-dimensional) map of the high-dimensional operational space of the tokamak. These maps provide a way of visualizing the structure of the high-dimensional plasma parameter space and allow discrimination between regions characterized by a high risk of disruption and those with a low risk of disruption. The data for this study comes from plasma discharges selected from 2005 and up to 2009 at JET. The self-organizing map and generative topographic mapping provide the most benefits in the visualization of very large and high-dimensional datasets. Some measures have been used to evaluate their performance. Special emphasis has been put on the position of outliers and extreme points, map composition, quantization errors and topological errors. (paper)

  14. Quark jets, gluon jets and the three-gluon vertex

    International Nuclear Information System (INIS)

    Fodor, Z.

    1989-11-01

    Using hadronic jets in electron-positron annihilation, we suggest a simple and model-independent method to see the differences between quark and gluon jets. We define and analyse special energy dependent moments of jets and choose those which are the most characteristic to the jet type. The method handles the energy of a jet in an adequate way. We discuss new methods using jet flavor tagging, ordinary flavor tagging of a definite quark jet or discrimination between quark and gluon jets, to test the triple-gluon vertex in electron-positron annihilation. An enriched sample of gluon jets, jets with the smallest energy in four-jet events, as well as a continuous tagging variable are also studied. 21 refs., 6 figs. (Author)

  15. Project and analysis of the toroidal magnetic field production circuits and the plasma formation of the ETE (Spherical Tokamak Experiment) tokamak

    International Nuclear Information System (INIS)

    Barbosa, Luis Filipe F.P.W.; Bosco, Edson del.

    1994-01-01

    This report presents the project and analysis of the circuit for production of the toroidal magnetic field in the Tokamak ETE (Spherical Tokamak Experiment). The ETE is a Tokamak with a small-aspect-ratio parameter to be used for studying the plasma physics for the research on thermonuclear fusion. This machine is being constructed at the Laboratorio Associado de Plasma (LAP) of the Instituto Nacional de Pesquisas Espaciais (INPE) in Sao Jose dos Campos, SP, Brazil. (author). 20 refs., 39 figs., 4 tabs

  16. LHCD experiments on tokamak CASTOR

    International Nuclear Information System (INIS)

    Zacek, F.; Badalec, J.; Jakubka, J.; Kryska, L.; Preinhaelter, J.; Stoeckel, J.; Valovic, M.; Nanobashvili, S.; Weixelbaum, L.; Wenzel, U.; Spineanu, F.; Vlad, M.

    1990-10-01

    A short survey is given of the experimental activities at the small Prague tokamak CASTOR. They concern primarily the LH current drive using multijunction waveguide grills as launching antennae. During two last years the, efforts were focused on a study of the electrostatic and magnetic fluctuations under conditions of combined inductive/LHCD regimes and of the relation of the level of these fluctuations to the anomalous particles transport in tokamak CASTOR. Results of the study are discussed in some detail. (author). 24 figs., 51 refs

  17. Measurement of the hydrogen recombination coefficient in the TEXT tokamak as a function of outgassing and power radiated during tokamak discharges

    International Nuclear Information System (INIS)

    Langley, R.A.; Rowan, W.L.; Bravenec, R.V.; Nelin, K.

    1986-10-01

    The global recombination rate coefficient k/sub r/ for hydrogen has been measured in the TEXT tokamak vacuum vessel for various surface conditions. An attempt was made to correlate the measured values of k/sub r/ with residual gas analyzer (RGA) data taken before each measurement of k/sub r/ and with the power radiated during tokamak discharges produced after each measurement of k/sub r/. The results show that k/sub r/ increases during a series of tokamak discharges, k/sub r/ is relatively insensitive to power radiated during tokamak discharges, and k/sub r/ increases with the RGA measurements of mass 28 and 40 but not with those of mass 18. In addition, it was found that the mass 18 (H 2 O) signal decreases as glow discharge experiments with hydrogen were performed

  18. Behavior of oxygen impurities in tokamak. Vol. 2

    Energy Technology Data Exchange (ETDEWEB)

    El-Sharif, R N; Beket, A H [Plasma and Nuclear Fusion Department, Nuclear Research Center, Atomic Energy Aurhority, Cairo (Egypt)

    1996-03-01

    Impurity transport in tokamak plasma is a subject of great importance in present day tokamak experiments. The transport of oxygen as an impurity element in small tokamak was studied theoretically. The viscosity coefficient of oxygen has been calculated in different approximation 13 and 21 moment approximation, taking into consideration {chi}>>1,{chi}{omega}{sub c} {tau}. It was found that in 21 moment approximation additional terms added to the perturbation from equilibrium leads to increase in viscosity coefficients than in 13 moments approximation. 9 figs.

  19. Transient electromagnetic analysis in tokamaks using TYPHOON code

    International Nuclear Information System (INIS)

    Belov, A.V.; Duke, A.E.; Korolkov, M.D.; Kotov, V.L.; Kukhtin, V.P.; Lamzin, E.A.; Sytchevsky, S.E.

    1996-01-01

    The transient electromagnetic analysis of conducting structures in tokamaks is presented. This analysis is based on a three-dimensional thin conducting shell model. The finite element method has been used to solve the corresponding integrodifferential equation. The code TYPHOON has been developed to calculate transient processes in tokamaks. Calculation tests and the code verification have been carried out. The calculation results of eddy current and force distibution and a.c. losses for different construction elements for both ITER and TEXTOR tokamaks magnetic systems are presented. (orig.)

  20. Tokamak Plasmas : Mirnov coil data analysis for tokamak ADITYA

    Indian Academy of Sciences (India)

    The spatial and temporal structures of magnetic signal in the tokamak ADITYA is analysed using recently developed singular value decomposition (SVD) technique. The analysis technique is first tested with simulated data and then applied to the ADITYA Mirnov coil data to determine the structure of current peturbation as ...

  1. Comparative studies of stellarator and tokamak transport

    Energy Technology Data Exchange (ETDEWEB)

    Stroth, U; Burhenn, R; Geiger, J; Giannone, L.; Hartfuss, H J; Kuehner, G; Ledl, L; Simmet, E E; Walter, H [Max-Planck-Inst. fuer Plasmaphysik, IPP-Euratom Association, Garching (Germany); ECRH Team; W7-AS Team

    1997-09-01

    Transport properties in the W7-AS stellarator and in tokamaks are compared. The parameter dependences and the absolute values of the energy confinement time are similar. Indications are found that the density dependence, which is usually observed in stellarator confinement, can vanish above a critical density. The density dependence in stellarators seems to be similar to that in the linear ohmic confinement regime, which, in small tokamaks, extends to high density values, too. Because of the similarity in the gross confinement properties, transport in stellarators and tokamaks should not be dominated by the parameters which are very different in the two concepts, i.e. magnetic shear, major rational values of the rotational transform and plasma current. A difference in confinement is that there exists evidence for pinches in the particle and, possibly, energy transport channels in tokamaks whereas in stellarators no pinches have been observed, so far. In order to study the effect of plasma current and toroidal electric fields, stellarator discharges were carried out with an increasing amount of plasma current. From these experiments, no clear evidence of a connection of pinches with these parameters is found. The transient response in W7-AS plasmas can be described in terms of a non-local model. As in tokamaks, also cold pulse experiments in W7-AS indicate the importance of non-local transport. (author). 8 refs, 5 figs.

  2. Predications and Observations of Global Beta-induced Alfven-acoustic Modes in JET and NSTX

    International Nuclear Information System (INIS)

    Gorelenkov, N.N.

    2008-01-01

    In this paper we report on observations and interpretations of a new class of global MHD eigenmode solutions arising in gaps in the low frequency Alfven-acoustic continuum below the geodesic acoustic mode frequency. These modes have been just reported (Gorelenkov et al 2007 Phys. Lett. 370 70-7) where preliminary comparisons indicate qualitative agreement between theory and experiment. Here we show a more quantitative comparison emphasizing recent NSTX experiments on the observations of the global eigenmodes, referred to as beta-induced Alfven-acoustic eigenmodes (BAAEs), which exist near the extrema of the Alfven-acoustic continuum. In accordance to the linear dispersion relations, the frequency of these modes may shift as the safety factor, q, profile relaxes. We show that BAAEs can be responsible for observations in JET plasmas at relatively low beta 20%. In NSTX plasma observed magnetic activity has the same properties as predicted by theory for the mode structure and the frequency. Found numerically in NOVA simulations BAAEs are used to explain the observed properties of relatively low frequency experimental signals seen in NSTX and JET tokamaks

  3. Experimental studies of Alfven modes stability on the JET tokamak

    International Nuclear Information System (INIS)

    Testa, D.; Fasoli, A.; Borba, D.N.

    2002-01-01

    The linear stability properties of Alfven modes are studied on JET using an active excitation technique. The Saddle Coils drive low amplitude, vertical bar δB/B vertical bar ∼ 10 -6 , stable plasma modes with toroidal mode number n=0 / 2. The diagnostic technique uses repetitive sweeps of the driving frequency in a pre-defined range, controlled in real-time. The plasma response is extracted from background noise using synchronous detection, and is used to identify in real-time the resonance corresponding to a global mode. When a resonance is found, the real-time controller locks to that frequency and tracks the mode. This provides a direct evaluation of the mode damping rate, γ/ω from the width of the frequency sweep. Two systems are used to measure fast fluctuation data. The KC1F system is a 8-channel, 1MHz/4s continuous digitizer used to analyze magnetic and reflectometry data in the frequency range 5≤f(kHz) ≤500. This system is particularly suitable to follow the time evolution of the instability. The CATS system collects and digitizes a large number of channels generally using short time snapshots. This system is useful to determine the position of the instability using the cross-correlation between the magnetic and other radially localized measurements, such as soft X-rays, reflectometry or electron cyclotron emission

  4. Spherical tokamak without external toroidal fields

    International Nuclear Information System (INIS)

    Kaw, P.K.; Avinash, K.; Srinivasan, R.

    2001-01-01

    A spherical tokamak design without external toroidal field coils is proposed. The tokamak is surrounded by a spheromak shell carrying requisite force free currents to produce the toroidal field in the core. Such equilibria are constructed and it is indicated that these equilibria are likely to have robust ideal and resistive stability. The advantage of this scheme in terms of a reduced ohmic dissipation is pointed out. (author)

  5. Vector boson tagged jets and jet substructure

    Directory of Open Access Journals (Sweden)

    Vitev Ivan

    2018-01-01

    Full Text Available In these proceedings, we report on recent results related to vector boson-tagged jet production in heavy ion collisions and the related modification of jet substructure, such as jet shapes and jet momentum sharing distributions. Z0-tagging and γ-tagging of jets provides new opportunities to study parton shower formation and propagation in the quark-gluon plasma and has been argued to provide tight constrains on the energy loss of reconstructed jets. We present theoretical predictions for isolated photon-tagged and electroweak boson-tagged jet production in Pb+Pb collisions at √sNN = 5.02 TeV at the LHC, addressing the modification of their transverse momentum and transverse momentum imbalance distributions. Comparison to recent ATLAS and CMS experimental measurements is performed that can shed light on the medium-induced radiative corrections and energy dissipation due to collisional processes of predominantly quark-initiated jets. The modification of parton splitting functions in the QGP further implies that the substructure of jets in heavy ion collisions may differ significantly from the corresponding substructure in proton-proton collisions. Two such observables and the implication of tagging on their evaluation is also discussed.

  6. Dynamic power balance analysis in JET

    International Nuclear Information System (INIS)

    Matthews, G F; Silburn, S A; Challis, C D; Iglesias, D; King, D; Eich, T; Sieglin, B; Contributors, JET

    2017-01-01

    The full scale realisation of nuclear fusion as an energy source requires a detailed understanding of power and energy balance in current experimental devices. In this we explore whether a global power balance model in which some of the calibration factors applied to the source or sink terms are fitted to the data can provide insight into possible causes of any discrepancies in power and energy balance seen in the JET tokamak. We show that the dynamics in the power balance can only be properly reproduced by including the changes in the thermal stored energy which therefore provides an additional opportunity to cross calibrate other terms in the power balance equation. Although the results are inconclusive with respect to the original goal of identifying the source of the discrepancies in the energy balance, we do find that with optimised parameters an extremely good prediction of the total power measured at the outer divertor target can be obtained over a wide range of pulses with time resolution up to ∼25 ms. (paper)

  7. Analysis of JET ELMy time series

    International Nuclear Information System (INIS)

    Zvejnieks, G.; Kuzovkov, V.N.

    2005-01-01

    Full text: Achievement of the planned operational regime in the next generation tokamaks (such as ITER) still faces principal problems. One of the main challenges is obtaining the control of edge localized modes (ELMs), which should lead to both long plasma pulse times and reasonable divertor life time. In order to control ELMs the hypothesis was proposed by Degeling [1] that ELMs exhibit features of chaotic dynamics and thus a standard chaos control methods might be applicable. However, our findings which are based on the nonlinear autoregressive (NAR) model contradict this hypothesis for JET ELMy time-series. In turn, it means that ELM behavior is of a relaxation or random type. These conclusions coincide with our previous results obtained for ASDEX Upgrade time series [2]. [1] A.W. Degeling, Y.R. Martin, P.E. Bak, J. B.Lister, and X. Llobet, Plasma Phys. Control. Fusion 43, 1671 (2001). [2] G. Zvejnieks, V.N. Kuzovkov, O. Dumbrajs, A.W. Degeling, W. Suttrop, H. Urano, and H. Zohm, Physics of Plasmas 11, 5658 (2004)

  8. Study of the triton-burnup process in different JET scenarios using neutron monitor based on CVD diamond

    Energy Technology Data Exchange (ETDEWEB)

    Nemtsev, G., E-mail: g.nemtsev@iterrf.ru; Amosov, V.; Meshchaninov, S.; Rodionov, R. [Institution “Project center ITER,” Moscow (Russian Federation); Popovichev, S. [CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Collaboration: EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB (United Kingdom)

    2016-11-15

    We present the results of analysis of triton burn-up process using the data from diamond detector. Neutron monitor based on CVD diamond was installed in JET torus hall close to the plasma center. We measure the part of 14 MeV neutrons in scenarios where plasma current varies in a range of 1-3 MA. In this experiment diamond neutron monitor was also able to detect strong gamma bursts produced by runaway electrons arising during the disruptions. We can conclude that CVD diamond detector will contribute to the study of fast particles confinement and help predict the disruption events in future tokamaks.

  9. Note: Measurement of the runaway electrons in the J-TEXT tokamak

    International Nuclear Information System (INIS)

    Chen, Z. Y.; Zhang, Y.; Zhang, X. Q.; Luo, Y. H.; Jin, W.; Li, J. C.; Chen, Z. P.; Wang, Z. J.; Yang, Z. J.; Zhuang, G.

    2012-01-01

    The runaway electrons have been measured by hard x-ray detectors and soft x-ray array in the J-TEXT tokamak. The hard x-ray radiations in the energy ranges of 0.5-5 MeV are measured by two NaI detectors. The flux of lost runaway electrons can be obtained routinely. The soft x-ray array diagnostics are used to monitor the runaway beam generated in disruptions since the soft x-ray is dominated by the interaction between runaway electrons and metallic impurities inside the plasma. With the aid of soft x-ray array, runaway electron beam has been detected directly during the formation of runaway current plateau following the disruptions.

  10. Tokamak residual zonal flow level in near-separatrix region

    International Nuclear Information System (INIS)

    Bing-Ren, Shi

    2010-01-01

    Residual zonal flow level is calculated for tokamak plasmas in the near-separatrix region of a diverted tokamak. A recently developed method is used to construct an analytic divertor tokamak configuration. It is shown that the residual zonal flow level becomes smaller but still keeps finite near the separatrix because the neoclassical polarisation mostly due to the trapped particles goes larger in this region. (fluids, plasmas and electric discharges)

  11. The audio and visual communication systems for suited engineering activities on JET

    International Nuclear Information System (INIS)

    Pearce, R.J.H.; Bruce, J.; Callaghan, C.; Hart, M.; Martin, P.; Middleton, R.; Tait, J.

    2001-01-01

    The beryllium and/or tritium contamination of the JET tokamak and auxiliary systems necessitates that many activities are carried out in air line fed pressurised suits. To enable often complex engineering activities to be performed, a number of novel audio and visual and communications systems have been designed. The paper describes these systems which give freedom of visual and audio communication between suited personnel, supervisors, operators and engineers. The system enhances the safety of the working environment as well as helping to minimise the radiation dose to personnel. It is concluded, from a number of years experience of using the audio and visual communications systems for suited operations, that safety and the progress of complex engineering tasks have been significantly enhanced

  12. The audio and visual communication systems for suited engineering activities on JET

    Energy Technology Data Exchange (ETDEWEB)

    Pearce, R.J.H. E-mail: robert.pearce@jet.uk; Bruce, J.; Callaghan, C.; Hart, M.; Martin, P.; Middleton, R.; Tait, J

    2001-11-01

    The beryllium and/or tritium contamination of the JET tokamak and auxiliary systems necessitates that many activities are carried out in air line fed pressurised suits. To enable often complex engineering activities to be performed, a number of novel audio and visual and communications systems have been designed. The paper describes these systems which give freedom of visual and audio communication between suited personnel, supervisors, operators and engineers. The system enhances the safety of the working environment as well as helping to minimise the radiation dose to personnel. It is concluded, from a number of years experience of using the audio and visual communications systems for suited operations, that safety and the progress of complex engineering tasks have been significantly enhanced.

  13. Physics aspects and technical elements of an ICRF heating system for JET

    International Nuclear Information System (INIS)

    Adam, J.; Jacquinot, J.; Kuus, H.

    1980-09-01

    We first present an overview of the recent results obtained in existing Tokamaks. These experiments offer a critical test of the basic physics ideas, give an estimate of the overall heating performance and show the degree of development of the RF hardware. A second part is devoted to the basic water-particle physics. JET will have to work in a wide variety of plasma parameters which constitutes an unprecedented constraint. A range of frequency is found which accomodates, within limits, most of the operating scenarios foreseen in JET. Moving from the plasma to the outer world, the wave coupling theory determines the position, the surface and the voltage stand-off of the launching structure which is necessary to transmit the power. Modules capable of transmitting 5 MW per Octant are discussed in the light of the present technology. The most critical parameter influencing the antenna performance appears to be the distance from the antenna to the plasma. Finally we have summarized our experience and our discussions with the industrial firms to outline the components of the RF system: power tubes, power supply requirements, coaxial transmission lines and matching network. A lay out of the power plant is then given

  14. The scientific program of the Tokamak de Varennes

    International Nuclear Information System (INIS)

    Daughney, C.C.

    1989-01-01

    The Tokamak de Varennes (TdeV) is the principal research tool of the Centre canadien de fusion magnetique (CCFM). This article places the Tokamak de Varennes within the framework of the Canadian National Fusion Program (NFP) and describes the scientific program of the TdeV as it was presented at the April 1989 meeting of the CCFM Advisory Committee. The CCFM scientific plant contains three main elements: tokamak development, research on transport and equilibrium in plasmas, and research on the plasma-wall problem. Phase I of the experimental program, commissioning the tokamak and the diagnostic systems, has been completed. Phase II of the experimental program will begin in December 1989 with the plasma boundary defined by a magnetic divertor and the power supplies and vacuum system capable of creating a sequence of one-second plasma pulses. (3 figs., 3 refs.) (L.L.)

  15. Second regime tokamak operation at large aspect ratio

    International Nuclear Information System (INIS)

    Navratil, G.A.

    1989-01-01

    This paper reviews the need for high beta in economic tokamak reactors and summarizes recent results on the scaling of the second regime beta limit for high-n ballooning modes using optimized pressure profiles as well as results on low-n mode stability at the first regime beta limit from the Columbia HBT tokamak. While several experiments have studied ballooning limits using high εβ p plasmas, the most important question for the use of the second stability regime for tokamak reactor improvement is how to achieve these high values of εβ p while at the same time increasing the value of beta to several times the Troyon beta limit. An approach to the study of this key question on beta limits using modest sized, large aspect ratio tokamaks is described. (author). 28 refs, 7 figs, 1 tab

  16. Hard X-ray studies on the Castor tokamak

    International Nuclear Information System (INIS)

    Mlynar, J.

    1990-04-01

    The electron runaway processes in tokamaks are discussed with regard to hard X radiation measurements. The origin and confinement of runaway electrons, their bremsstrahlung spectra and the influence of lower hybrid current drive on the distribution of high-energy electrons are analyzed for the case of the Castor tokamak. The hard X-ray spectrometer designed for the Castor tokamak is also described and preliminary qualitative results of hard X-ray measurements are presented. The first series of integral measurements made it possible to map the azimuthal dependence of the hard X radiation

  17. Real-time horizontal position control for Aditya-upgrade tokamak

    International Nuclear Information System (INIS)

    Kumar, Rohit; Ghosh, Joydeep; Tanna, Rakesh L.

    2015-01-01

    Position of plasma column is required to be controlled in real time for improved operation of any tokamak. A PID based system for real-time horizontal plasma position control has been designed for Aditya Upgrade tokamak. Modelling of transfer functions of actuators, plasma and diagnostic system are carried out for ADITYA-U tokamak. The PID controller is optimized using MATLAB-SIMULINK for horizontal position control. Further feed-forward loop is implemented where disturbance due to density variation is suppressed, which results in improved performance as compared to conventional PID operation. In this paper the detailed design of the whole system for real time control of plasma horizontal position in Aditya Upgrade tokamak is presented. (author)

  18. Varennes Tokamak

    International Nuclear Information System (INIS)

    Cumyn, P.B.

    A consortium of five organizations under the leadership of IREQ, the Institute de Recherche d'Hydro-Quebec has completed a conceptual design study for a tokamak device, and in January 1981 its construction was authorized with funding being provided principally by Hydro-Quebec and the National Research Council, as well as by the Ministre d'Education du Quebec and Natural Sciences and Engineering Research Council of Canada (NSERC). The device will form the focus of Canada's magnetic-fusion program and will be located in IREQ's laboratories in Varennes. Presently the machine layout is being finalized from the physics point of view and work has started on equipment design and specification. The Tokamak de Varennes will be an experimental device, the purpose of which is to study plasma and other fusion related phenomena. In particular it will study: 1. Plasma impurities and plasma/liner interaction; 2. Long pulse or quasi-continuous operation using plasma rampdown and eventually plasma current reversal in order to maintain the plasma; and 3. Advanced diagnostics

  19. Tokamak WEST připraven ke startu!

    Czech Academy of Sciences Publication Activity Database

    Řípa, Milan

    Květen (2017) ISSN 2464-7888 Institutional support: RVO:61389021 Keywords : fusion * ITER * tokamak * WEST * Tora Supra * divertor Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) http://www.3pol.cz/cz/rubriky/jaderna-fyzika-a-energetika/2014-tokamak-west-pripraven-ke- start u

  20. Predictive modelling of edge transport phenomena in ELMy H-mode tokamak fusion plasmas

    International Nuclear Information System (INIS)

    Loennroth, J.-S.

    2009-01-01

    the first ballooning stable region in magnetohydrodynamics (MHD). The result may have implications on the control of ELMs and performance in future tokamaks. Modest pedestal performance and benign ELMs observed in the presence of toroidal magnetic field ripple in dimensionless pedestal identity experiments between the JET and JT-60U tokamaks are explained through predictive transport modelling as resulting from ripple-induced thermal ion losses, nondiffusive (direct) losses to be specific. It is shown that ripple losses need not necessarily have a detrimental influence on performance, but that there is a trade-off between performance and benignity of ELMs. The results may have widely felt implications, because ITER, the next major facility on the way towards a commercial fusion reactor, is foreseen to operate with a non-negligible level of toroidal magnetic field ripple. (orig.)

  1. Correlation of the tokamak H-mode density limit with ballooning stability at the separatrix

    Science.gov (United States)

    Eich, T.; Goldston, R. J.; Kallenbach, A.; Sieglin, B.; Sun, H. J.; ASDEX Upgrade Team; Contributors, JET

    2018-03-01

    We show for JET and ASDEX Upgrade, based on Thomson-scattering measurements, a clear correlation of the density limit of the tokamak H-mode high-confinement regime with the approach to the ideal ballooning instability threshold at the periphery of the plasma. It is shown that the MHD ballooning parameter at the separatrix position α_sep increases about linearly with the separatrix density normalized to Greenwald density, n_e, sep/n_GW for a wide range of discharge parameters in both devices. The observed operational space is found to reach at maximum n_e, sep/n_GW≈ 0.4 -0.5 at values for α_sep≈ 2 -2.5, in the range of theoretical predictions for ballooning instability. This work supports the hypothesis that the H-mode density limit may be set by ballooning stability at the separatrix.

  2. Tokamak reactor startup power

    International Nuclear Information System (INIS)

    Weldon, D.M.; Murray, J.G.

    1983-01-01

    Tokamak startup with ohmic heating (OH)-induced voltages requires rather large voltages and power supplies. On present machines, with no radiofrequency (rf)-assist provisions, hundreds of volts have been specified for their designs. With the addition of electron cyclotron resonant heating (ECRH) assist, the design requirements have been lowered. To obtain information on the cost and complexity associated with this ECRH-assisted, OH-pulsed startup voltage for ignition-type machines, a trade-off study was completed. The Fusion Engineering Device (FED) configuration was selected as a model because information was available on the structure. The data obtained are applicable to all tokamaks of this general size and complexity, such as the Engineering Test Reactor

  3. Conceptual design of a commercial tokamak reactor using resistive magnets

    International Nuclear Information System (INIS)

    LeClaire, R.J. Jr.

    1988-01-01

    The future of the tokamak approach to controlled thermonuclear fusion depends in part on its potential as a commercial electricity-producing device. This potential is continually being evaluated in the fusion community using parametric, system, and conceptual studies of various approaches to improving tokamak reactor design. The potential of tokamaks using resistive magnets as commercial electricity-producing reactors is explored. Parametric studies have been performed to examine the major trade-offs of the system and to identify the most promising configurations for a tokamak using resistive magnets. In addition, a number of engineering issues have been examined including magnet design, blanket/first-wall design, and maintenance. The study indicates that attractive design space does exist and presents a conceptual design for the Resistive Magnet Commercial Tokamak Reactor (RCTR). No issue has been identified, including recirculating power, that would make the overall cost of electricity of RCTR significantly different from that of a comparably sized superconducting tokamak. However, RCTR may have reliability and maintenance advantages over commercial superconducting magnet devices

  4. Time - resolved thermography at Tokamak T-10

    International Nuclear Information System (INIS)

    Grunow, C.; Guenther, K.; Lingertat, J.; Chicherov, V.M.; Evstigneev, S.A.; Zvonkov, S.N.

    1987-01-01

    Thermographic experiments were performed at T-10 tokamak to investigate the thermic coupling of plasma and the limiter. The limiter is an internal equipment of the vacuum vessel of tokamak-type fusion devices and the interaction of plasma with limiter results a high thermal load of limiter for short time. In according to improve the limiter design the temperature distribution on the limiter surface was measured by a time-resolved thermographic method. Typical isotherms and temperature increment curves are presented. This measurement can be used as a systematic plasma diagnostic method because the limiter is installed in the tokamak whereas special additional probes often disturb the plasma discharge. (D.Gy.) 3 refs.; 7 figs

  5. Study on assembly techniques and procedures for ITER tokamak device

    International Nuclear Information System (INIS)

    Obara, Kenjiro; Kakudate, Satoshi; Shibanuma, Kiyoshi; Sago, Hiromi; Ue, Koichi; Shimizu, Katsusuke; Onozuka, Masanori

    2006-06-01

    The International Thermonuclear Experimental Reactor (ITER) tokamak is mainly composed of a doughnut-shaped vacuum vessel (VV), four types of superconducting coils such as toroidal field coils (TF coils) arranged around the VV, and in-vessel components, such as blanket and divertor. The dimensions and weight of the respective components are around a few ten-meters and several hundred-tons. In addition, the whole tokamak assembly, which are composed of these components, are roughly estimated, 26 m in diameter, 18 m in height and over 16,500 tons in total weight. On the other hand, as for positioning and assembly tolerances of the VV and the TF coil are required to be a high accuracy of ±3 mm in spite of large size and heavy weight. The assembly procedures and techniques of the ITER tokamak are therefore studied, taking account of the tolerance requirements as well as the configuration of the tokamak with large size and heavy weight. Based on the above backgrounds, the assembly procedures and techniques, which are able to assemble the tokamak with high accuracy, are described in the present report. The tokamak assembly operations are categorized into six work break down structures (WBS), i.e., (1) preparation for assembly operations, (2) sub-assembly of the 40deg sector composed of 40deg VV sector, two TF coils and thermal shield between VV and TF coil at the assembly hall, (3) completion of the doughnut-shaped tokamak assembly composed of nine 40deg sectors in the cryostat at the tokamak pit, (4) measurement of positioning and accuracy after the completion of the tokamak assembly, (5) installation of the ex-vessel components, and (6) installation of in-vessel components. In the present report, two assembly operations of (2) and (3) in the above six WBS, which are the most critical in the tokamak assembly, are mainly described. The report describes the following newly developed tokamak assembly procedures and techniques, jigs and tools for assembly and metrology

  6. A dimensionless criterion for characterising internal transport barriers in tokamaks

    International Nuclear Information System (INIS)

    Tresset, G.; Litaudon, X.; Moreau, D.

    2000-07-01

    A simple criterion, based on a dimensionless parameter (ρ T * =ρ s /L T ) related to drift wave turbulence stabilisation and anomalous transport theory, is proposed in order to characterise the emergence and the space-time evolution of internal transport barriers (ITB's) during a tokamak discharge. The underlying physics which led us to consider the possible relevance of this parameter as a local indicator of a bifurcated plasma state is the breaking of the gyro-Bohm turbulence scaling by the diamagnetic velocity shear, which has been observed in various numerical simulations [e.g. X. Garbet and R.E. Waltz, Phys. Plasmas 3(1996) 1898]. The presence of an ITB is inferred when ρ T * exceeds a threshold value. The main features like the emergence time, location and even dynamics of ITB's can then be summarized on a single graphical representation consistent with measurement uncertainties. The validity of such a criterion is demonstrated on the Optimized Shear (OS) database of JET in several experimental configurations. Large database analysis and realtime control of OS discharges are envisaged as the most attractive applications. (author)

  7. Contributions to 4th European fusion theory conference (Aspenaes, Sweden, 17th-19th June 1991)

    International Nuclear Information System (INIS)

    1991-11-01

    Papers contributed by the JET team are presented. Studies on ion cyclotron-resonance heating in the JET tokamak are included. Other topics covered are the destruction of drift surfaces in tokamak devices, the neoclassical impurity flux in the presence of anomalous transport, and nonlinear regimes in plasmas. (UK)

  8. Trajectory planning of tokamak flexible in-vessel inspection robot

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hesheng [Department of Automation, Shanghai Jiao Tong University, 200240 Shanghai (China); Key Laboratory of System Control and Information Processing, Ministry of Education of China, 200240 Shanghai (China); Chen, Weidong, E-mail: wdchen@sjtu.edu.cn [Department of Automation, Shanghai Jiao Tong University, 200240 Shanghai (China); Key Laboratory of System Control and Information Processing, Ministry of Education of China, 200240 Shanghai (China); Lai, Yinping; He, Tao [Department of Automation, Shanghai Jiao Tong University, 200240 Shanghai (China); Key Laboratory of System Control and Information Processing, Ministry of Education of China, 200240 Shanghai (China)

    2015-10-15

    Highlights: • A tokamak flexible in-vessel inspection robot is designed. • Two trajectory planning methods are used to ensure the full coverage of the first wall scanning. • The method is tested on a simulated platform of EAST with the flexible in-vessel inspection robot. • Experimental results show the effectiveness of the proposed algorithm. - Abstract: Tokamak flexible in-vessel inspection robot is mainly designed to carry a camera for close observation of the first wall of the vacuum vessel, which is essential for the maintenance of the future tokamak reactor without breaking the working condition of the vacuum vessel. A tokamak flexible in-vessel inspection robot is designed. In order to improve efficiency of the remote maintenance, it is necessary to design a corresponding trajectory planning algorithm to complete the automatic full coverage scanning of the complex tokamak cavity. Two different trajectory planning methods, RS (rough scanning) and FS (fine scanning), according to different demands of the task, are used to ensure the full coverage of the first wall scanning. To quickly locate the damage position, the first trajectory planning method is targeted for quick and wide-ranging scan of the tokamak D-shaped section, and the second one is for careful observation. Furthermore, both of the two different trajectory planning methods can ensure the full coverage of the first wall scanning with an optimal end posture. The method is tested on a simulated platform of EAST (Experimental Advanced Superconducting Tokamak) with the flexible in-vessel inspection robot, and the results show the effectiveness of the proposed algorithm.

  9. Trajectory planning of tokamak flexible in-vessel inspection robot

    International Nuclear Information System (INIS)

    Wang, Hesheng; Chen, Weidong; Lai, Yinping; He, Tao

    2015-01-01

    Highlights: • A tokamak flexible in-vessel inspection robot is designed. • Two trajectory planning methods are used to ensure the full coverage of the first wall scanning. • The method is tested on a simulated platform of EAST with the flexible in-vessel inspection robot. • Experimental results show the effectiveness of the proposed algorithm. - Abstract: Tokamak flexible in-vessel inspection robot is mainly designed to carry a camera for close observation of the first wall of the vacuum vessel, which is essential for the maintenance of the future tokamak reactor without breaking the working condition of the vacuum vessel. A tokamak flexible in-vessel inspection robot is designed. In order to improve efficiency of the remote maintenance, it is necessary to design a corresponding trajectory planning algorithm to complete the automatic full coverage scanning of the complex tokamak cavity. Two different trajectory planning methods, RS (rough scanning) and FS (fine scanning), according to different demands of the task, are used to ensure the full coverage of the first wall scanning. To quickly locate the damage position, the first trajectory planning method is targeted for quick and wide-ranging scan of the tokamak D-shaped section, and the second one is for careful observation. Furthermore, both of the two different trajectory planning methods can ensure the full coverage of the first wall scanning with an optimal end posture. The method is tested on a simulated platform of EAST (Experimental Advanced Superconducting Tokamak) with the flexible in-vessel inspection robot, and the results show the effectiveness of the proposed algorithm.

  10. HESTER: a hot-electron superconducting tokamak experimental reactor at M.I.T

    International Nuclear Information System (INIS)

    Schultz, J.H.; Montgomery, D.B.

    1983-04-01

    HESTER is an experimental tokamak, designed to resolve many of the central questions in the tokamak development program in the 1980's. It combines several unique features with new perspectives on the other major tokamak experiments scheduled for the next decade. The overall objectives of HESTER, in rough order of their presently perceived importance, are the achievement of reactor-like wall-loadings and plasma parameters for long pulse periods, determination of a good, reactor-relevant method of steady-state or very long pulse tokamak current drive, duplication of the planned very high temperature neutral injection experiments using only radio frequency heating, a demonstration of true steady-state tokamak operation, integration of a high-performance superconducting magnet system into a tokamak experiment, determination of the best methods of long term impurity control, and studies of transport and pressure limits in high field, high aspect ratio tokamak plasmas. These objectives are described

  11. Dynamics of Plasma Jets and Bubbles Launched into a Transverse Background Magnetic Field

    Science.gov (United States)

    Zhang, Yue

    2017-10-01

    A coaxial magnetized plasma gun has been utilized to launch both plasma jets (open B-field) and plasma bubbles (closed B-field) into a transverse background magnetic field in the HelCat (Helicon-Cathode) linear device at the University of New Mexico. These situations may have bearing on fusion plasmas (e.g. plasma injection for tokamak fueling, ELM pacing, or disruption mitigation) and astrophysical settings (e.g. astrophysical jet stability, coronal mass ejections, etc.). The magnetic Reynolds number of the gun plasma is 100 , so that magnetic advection dominates over magnetic diffusion. The gun plasma ram pressure, ρjetVjet2 >B02 / 2μ0 , the background magnetic pressure, so that the jet or bubble can easily penetrate the background B-field, B0. When the gun axial B-field is weak compared to the gun azimuthal field, a current-driven jet is formed with a global helical magnetic configuration. Applying the transverse background magnetic field, it is observed that the n = 1 kink mode is stabilized, while magnetic probe measurements show contrarily that the safety factor q(a) drops below unity. At the same time, a sheared axial jet velocity is measured. We conclude that the tension force arising from increasing curvature of the background magnetic field induces the measured sheared flow gradient above the theoretical kink-stabilization threshold, resulting in the emergent kink stabilization of the injected plasma jet. In the case of injected bubbles, spheromak-like plasma formation is verified. However, when the spheromak plasma propagates into the transverse background magnetic field, the typical self-closed global symmetry magnetic configuration does not hold any more. In the region where the bubble toroidal field opposed the background B-field, the magneto-Rayleigh-Taylor (MRT) instability has been observed. Details of the experiment setup, diagnostics, experimental results and theoretical analysis will be presented. Supported by the National Science Foundation

  12. On the HL-1M tokamak plasma confinement time

    International Nuclear Information System (INIS)

    Qin Yunwen

    2001-01-01

    Emphasizing that the tokamak plasma confinement time is the plasma particle or thermal energy loss characteristic time, the relevant physical concept and HL-1M tokamak experimental data analyses are reviewed

  13. Digital control of plasma position in Damavand tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Emami, M.; Babazadeh, A.R.; Roshan, M.V.; Memarzadeh, M.; Habibi, H. [Atomic Energy Organization of Iran (AEOI), Tehran (Iran, Islamic Republic of). Nuclear Fusion Research Center. Plasma Physics Lab.

    2002-03-01

    Plasma position control is one of the important issues in the design and operation of tokamak fusion research device. Since a tokamak is basically an electrical system consisting of power supplies, coils, plasma and eddy currents, a model in which these components are treated as an electrical circuits is used in designing Damavand plasma position control system. This model is used for the simulation of the digital control system and its parameters have been verified experimentally. In this paper, the performance of a high-speed digital controller as well as a simulation study and its application to the Damavand tokamak is discussed. (author)

  14. A computer code for Tokamak reactor concepts evaluation

    International Nuclear Information System (INIS)

    Rosatelli, F.; Raia, G.

    1985-01-01

    A computer package has been developed which could preliminarily investigate the engineering configuration of a tokamak reactor concept. The code is essentially intended to synthesize, starting from a set of geometrical and plasma physics parameters and the required performances and objectives, three fundamental components of a tokamak reactor core: blanket+shield, TF magnet, PF magnet. An iterative evaluation of the size, power supply and cooling system requirements of these components allows the judgment and the preliminary design optimization on the considered reactor concept. The versatility of the code allows its application both to next generation tokamak devices and power reactor concepts

  15. 3He functions in tokamak-pumped laser systems

    International Nuclear Information System (INIS)

    Jassby, D.L.

    1986-10-01

    3 He placed in an annular cell around a tokamak fusion generator can convert moderated fusion neutrons to energetic ions by the 3 He(n,p)T reaction, and thereby excite gaseous lasants mixed with the 3 He while simultaneously breeding tritium. The total 3 He inventory is about 4 kg for large tokamak devices. Special configurations of toroidal-field magnets, neutron moderators and beryllium reflectors are required to permit nearly uniform neutron current into the laser cell with minimal attenuation. The annular laser radiation can be combined into a single output beam at the top of the tokamak

  16. Analysis of EAST tokamak cryostat anti-seismic performance

    International Nuclear Information System (INIS)

    Chen Wei; Kong Xiaoling; Liu Sumei; Ni Xiaojun; Wang Zhongwei

    2014-01-01

    A 3-D finite element model for EAST tokamak cryostat is established by using ANSYS. On the basis of the modal analysis, the seismic response of the EAST tokamak cryostat structure is calculated according to an input of the design seismic response spectrum referring to code for seismic design of nuclear power plants. Calculation results show that EAST cryostat displacement and stress response is small under the action of earthquake. According to the standards, EAST tokamak cryostat structure under the action of design seismic can meet the requirements of anti-seismic design intensity, and ensure the anti-seismic safety of equipment. (authors)

  17. Characterization of the Tokamak Novillo in cleaning regime

    International Nuclear Information System (INIS)

    Lopez C, R.; Melendez L, L.; Valencia A, R.; Chavez A, E.; Colunga S, S.; Gaytan G, E.

    1992-02-01

    In this work the obtained results of the investigation about the experimental characterization of those low energy pulsed discharges of the Tokamak Novillo are reported. With this it is possible to fix the one operation point but appropriate of the Tokamak to condition the chamber in the smallest possible time for the cleaning discharges regime before beginning the main discharge. The characterization of the cleaning discharges in those Tokamaks is an unique process and characteristic of each device, since the good points of operation are consequence of those particularities of the design of the machine. In the case of the Tokamak Novillo, besides characterizing it a contribution is made to the cleaning discharges regime which consists on the one product of the current peak to peak of plasma by the duration of the discharge Ip t like reference parameter for the optimization of the operation of the device in the cleaning discharge regime. The maximum value of the parameter I (p) t, under different work conditions, allowed to find the good operation point to condition the discharges chamber of the Tokamak Novillo in short time and to arrive to a regime in which is not necessary the preionization for the obtaining of the cleaning discharges. (Author)

  18. Spatial distribution of {gamma} emissivity and fast ions during ({sup 3}He)D ICRF heating experiments on JET

    Energy Technology Data Exchange (ETDEWEB)

    Start, D F.H. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Righi, E [Imperial Coll. of Science and Technology, London (United Kingdom); Warrick, C [UKAEA Culham Lab., Abingdon (United Kingdom)

    1994-07-01

    A model is presented that can simulate the {gamma} emissivity in the poloidal cross-section during ({sup 3}He)D ICRF heated discharges in JET plasmas, by merging information obtained from the fast ion distribution and from nuclear reactions producing the observed {gamma} emissivity (production of {gamma} photons during {sup 3}He-{sup 9}Be reactions). This technique can play an important role in the identification of plasma instabilities that affect the redistribution of the fast ions in the plasma, like the TAE modes and the ripple in the tokamak magnetic field. 9 refs., 4 figs., 1 tab.

  19. Advanced tokamak physics in DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Petty, C.C.; Luce, T.C.; Politzer, P.A.; Bray, B.; Burrell, K.H.; Chu, M.S.; Ferron, J.R.; Gohil, P.; Greenfield, C.M.; Hsieh, C.-L.; Hyatt, A.W.; La Haye, R.J.; Lao, L.L.; Leonard, A.W.; Lin-Liu, Y.R.; Lohr, J.; Mahdavi, M.A.; Petrie, T.W.; Pinsker, R.I.; Prater, R.; Scoville, J.T.; Staebler, G.M.; Strait, E.J.; Taylor, T.S.; West, W.P. [General Atomics, PO Box 85608, San Diego, CA (United States); Wade, M.R.; Lazarus, E.A.; Murakami, M. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Allen, S.L.; Casper, T.A.; Jayakumar, R.; Lasnier, C.J.; Makowski, M.A.; Rice, B.W.; Wolf, N.S. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Austin, M.E. [University of Texas, Austin, TX (United States); Fredrickson, E.D.; Gorelov, I.; Johnson, L.C.; Okabayashi, M.; Wong, K.-L. [Princeton Plasma Physics Laboratory, Princeton, NJ (United States); Garofalo, A.M.; Navratil, G.A. [Columbia University, New York (United States); Heidbrink, W. [University of California, Irvine, CA (United States); Kinsey, J.E. [Leheigh University, Bethlehem, PA (United States); McKee, G.R. [University of Wisconsin, Madison, WI (United States); Rettig, C.L.; Rhodes, T.L. [University of California, Los Angeles, CA (United States); Watkins, J.G. [Sandia National Laboratories, Albuquerque, NM (United States)

    2000-12-01

    Advanced tokamaks seek to achieve a high bootstrap current fraction without sacrificing fusion power density or fusion gain. Good progress has been made towards the DIII-D research goal of demonstrating a high-{beta} advanced tokamak plasma in steady state with a relaxed, fully non-inductive current profile and a bootstrap current fraction greater than 50%. The limiting factors for transport, stability, and current profile control in advanced operating modes are discussed in this paper. (author)

  20. Progress towards steady-state operation and real time control of internal transport barriers in JET

    International Nuclear Information System (INIS)

    Litaudon, X.; Becoulet, A.; Crisanti, F.

    2003-01-01

    In JET advanced tokamak research mainly focuses on plasmas with internal transport barriers (ITBs), generated by modifications of the current profile. The formerly developed optimised shear regime with low magnetic shear in the plasma center has been extended to deeply reversed magnetic shear configurations. High fusion performance with wide ITBs has been obtained transiently in deeply reversed magnetic shear configuration: H IPB98(y,2) ∼1.9, β N =2.4 at I p =2.5MA. At somewhat reduced performance electron and ion ITBs have been sustained in full current drive operation with 1MA of bootstrap current: H IPB98(y,2) ∼1, β N =1.7 at I p =2.0MA. The ITBs have been maintained up to 11s. This duration, much larger than the energy confinement time (37 times larger), is already approaching a current resistive time. New real-time measurements and feedback control algorithms have been developed and implemented in JET for successfully controlling the ITB dynamics and the current density profile in the highly non-inductive regime. (author)

  1. Technology and physics in the Tokamak Program: The need for an integrated, steady-state RandD tokamak experiment

    International Nuclear Information System (INIS)

    1988-05-01

    The Steady-state Tokamak (STE) Experiment is a proposed superconducting-coil, hydrogen-plasma tokamak device intended to address the integrated non-nuclear issues of steady state, high-power tokamak physics and technology. Such a facility has been called for in the US program plan for the mid 1990's, and will play a unique role in the world-wide fusion effort. Information from STE on steady-state current drive, plasma control, and high power technology will contribute significantly to the operating capabilities of future steady-state devices. This paper reviews preliminary designs and expected technological contributions to the US and world fusion reactor research from each of the above mentioned reactor systems. This document is intended as a proposal and feasibility discussion and does not include exhaustive technical reviews. 12 figs., 3 tabs

  2. The ARIES tokamak fusion reactor study

    International Nuclear Information System (INIS)

    Bartlit, J.R.; Bathke, C.G.; Krakowski, R.A.; Miller, R.L.; Beecraft, W.R.; Hogan, J.T.; Peng, Y.K.M.; Reid, R.L.; Strickler, D.J.; Whitson, J.C.; Blanchard, J.P.; Emmert, G.A.; Santarius, J.F.; Sviatoslavsky, I.N.; Wittenberg, L.J.

    1989-01-01

    The ARIES study is a community effort to develop several visions of the tokamak as fusion power reactors. The aims are to determine their potential economics, safety, and environmental features and to identify physics and technology areas with the highest leverage for achieving the best tokamak reactor. Three ARIES visions are planned, each having a different degree of extrapolation from the present data base in physics and technology. The ARIES-I design assumes a minimum extrapolation from current tokamak physics (e.g., 1st stability) and incorporates technological advances that can be available in the next 20 to 30 years. ARIES-II is a DT-burning tokamak in 2nd stability regime and employs both potential advances in the physics and expected advances in technology and engineering; and ARIES-III is a conceptual D 3 He reactor. This paper focuses on the ARIES-I design. Parametric systems studies show that the optimum 1st stability tokamak has relatively low plasma current (∼ 12 MA), high plasma aspect ratio (∼ 4-6), and high magnetic field (∼ 24 T at the coil). ARIES-I is 1,000 MWe (net) reactor with a plasma major radius of 6.5 m, a minor radius of 1.4 m, a neutron wall loading of about 2.8 MW/m 2 , and a mass power density of about 90 kWe/ton. The ARIES-I reactor operates at steady state using ICRF fast waves to drive current in the plasma core and lower-hybrid waves for edge-plasma current drive. The current-drive system supplements a significant (∼ 57%) bootstrap current contribution. The impurity control system is based on high-recycling poloidal divertors. Because of the high field and large Lorentz forces in the toroidal-field magnets, innovative approaches with high-strength materials and support structures are used. 24 refs., 4 figs., 1 tab

  3. STARFIRE: a commercial tokamak reactor

    International Nuclear Information System (INIS)

    1979-12-01

    The purpose of this document is to provide an interim status report on the STARFIRE project for the period of May to September 1979. The basic objective of the STARFIRE project is to develop a design concept for a commercial tokamak fusion electric power plant based on the deuterium/tritium/lithium fuel cycle. The key technical objective is to develop the best embodiment of the tokamak as a power reactor consistent with credible engineering solutions to design problems. Another key goal of the project is to give careful attention to the safety and environmental features of a commercial fusion reactor

  4. Operating tokamaks with steady-state toroidal current

    International Nuclear Information System (INIS)

    Fisch, N.J.

    1981-04-01

    Continuous operation of a tokamak requires, among other things, a means of continuously providing the toroidal current. Various methods have been proposed to provide this current including methods which utilize radio-frequency waves in any of several frequency regimes. Here we elaborate on the prospects of incorporating these current-drive techniques in tokamak reactors, concentrating on the theoretical minimization of the power requirements

  5. Effect of impurity radiation on tokamak equilibrium

    International Nuclear Information System (INIS)

    Rebut, P.H.; Green, B.J.

    1977-01-01

    The energy loss from a tokamak plasma due to the radiation from impurities is of great importance in the overall energy balance. Taking the temperature dependence of this loss for two impurities characteristic of those present in existing tokamak plasmas, the condition for radial power balance is derived. For the impurities considered (oxygen and iron) it is found that the radiation losses are concentrated in a thin outer layer of the plasma and the equilibrium condition places an upper limit on the plasma paraticle number density in this region. This limiting density scales with mean current density in the same manner as is experimentally observed for the peak number density of tokamak plasmas. The stability of such equilibria is also discussed. (author)

  6. Activation analysis of the compact ignition tokamak

    International Nuclear Information System (INIS)

    Selcow, E.C.

    1986-01-01

    The US fusion program has completed the conceptual design of a compact tokamak device that achieves ignition. The high neutron wall loadings associated with this compact deuterium-tritium-burning device indicate that radiation-related issues may be significant considerations in the overall system design. Sufficient shielding will be requied for the radiation protection of both reactor components and occupational personnel. A close-in igloo shield has been designed around the periphery of the tokamak structure to permit personnel access into the test cell after shutdown and limit the total activation of the test cell components. This paper describes the conceptual design of the igloo shield system and discusses the major neutronic concerns related to the design of the Compact Ignition Tokamak

  7. Ripple induced trapped particle loss in tokamaks

    International Nuclear Information System (INIS)

    White, R.B.

    1996-05-01

    The threshold for stochastic transport of high energy trapped particles in a tokamak due to toroidal field ripple is calculated by explicit construction of primary resonances, and a numerical examination of the route to chaos. Critical field ripple amplitude is determined for loss. The expression is given in magnetic coordinates and makes no assumptions regarding shape or up-down symmetry. An algorithm is developed including the effects of prompt axisymmetric orbit loss, ripple trapping, convective banana flow, and stochastic ripple loss, which gives accurate ripple loss predictions for representative Tokamak Fusion Test Reactor and International Thermonuclear Experimental Reactor equilibria. The algorithm is extended to include the effects of collisions and drag, allowing rapid estimation of alpha particle loss in tokamaks

  8. Magnetohydrodynamic Waves and Instabilities in Rotating Tokamak Plasmas

    NARCIS (Netherlands)

    J.W. Haverkort (Willem)

    2013-01-01

    htmlabstractOne of the most promising ways to achieve controlled nuclear fusion for the commercial production of energy is the tokamak design. In such a device, a hot plasma is confined in a toroidal geometry using magnetic fields. The present generation of tokamaks shows significant plasma

  9. DeepJet: a deep-learned multiclass jet-tagger for slim and fat jets

    CERN Multimedia

    CERN. Geneva; Qu, Huilin; Stoye, Markus; Kieseler, Jan; Verzetti, Mauro

    2018-01-01

    We present a customized neural network architecture for both, slim and fat jet tagging. It is based on the idea to keep the concept of physics objects, like particle flow particles, as a core element of the network architecture. The deep learning algorithm works for most of the common jet classes, i.e. b, c, usd and gluon jets for slim jets and W, Z, H, QCD and top classes for fat jets. The developed architecture promising gains in performance as shown in simulation of the CMS collaboration. Currently the tagger is under test in real data in the CMS experiment.

  10. Theory of tokamak plasmas

    Energy Technology Data Exchange (ETDEWEB)

    White, R B [Princeton Univ., NJ (USA). Plasma Physics Lab.

    1989-01-01

    The book covers the consequences of ideal and resistive magnetohydrodynamics, these theories being responsible for most of what is well understood regarding the physics of tokamak discharges. The focus is on the description of equilibria, the linear and nonlinear theory of large scale modes, and single particle guiding center motion, including simple neoclassical effects. modern methods of general magnetic coordinates are used, and the student is introduced to the onset of chaos in Hamiltonian systems in the discussion of destruction of magnetic surfaces. Much of the book is devoted to the description of the limitations placed on tokamak operating parameters given by ideal and resistive modes, and current ideas about how to extend and optimize these parameters. (author). refs.; figs.

  11. Axisymmetric tokamak scapeoff transport

    International Nuclear Information System (INIS)

    Singer, C.E.; Langer, W.D.

    1982-08-01

    We present the first self-consistent estimate of the magnitude of each term in a fluid treatment of plasma transport for a plasma lying in regions of open field lines in an axisymmetric tokamak. The fluid consists of a pure hydrogen plasma with sources which arise from its interaction with neutral hydrogen atoms. The analysis and results are limited to the high collisionality regime, which is optimal for a gaseous neutralizer divertor, or to a cold plasma mantle in a tokamak reactor. In this regime, both classical and neoclassical transport processes are important, and loss of particles and energy by diamagnetic flow are also significant. The prospect of extending the analysis to the lower collisionality regimes encountered in many existing experiments is discussed

  12. Realizing steady-state tokamak operation for fusion energy

    International Nuclear Information System (INIS)

    Luce, T. C.

    2011-01-01

    Continuous operation of a tokamak for fusion energy has clear engineering advantages but requires conditions beyond those sufficient for a burning plasma. The fusion reactions and external sources must support both the pressure and the current equilibrium without inductive current drive, leading to demands on stability, confinement, current drive, and plasma-wall interactions that exceed those for pulsed tokamaks. These conditions have been met individually, and significant progress has been made in the past decade to realize scenarios where the required conditions are obtained simultaneously. Tokamaks are operated routinely without disruptions near pressure limits, as needed for steady-state operation. Fully noninductive sustainment with more than half of the current from intrinsic currents has been obtained for a resistive time with normalized pressure and confinement approaching those needed for steady-state conditions. One remaining challenge is handling the heat and particle fluxes expected in a steady-state tokamak without compromising the core plasma performance.

  13. Gamma ray imager on the DIII-D tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Pace, D. C., E-mail: pacedc@fusion.gat.com; Taussig, D.; Eidietis, N. W.; Van Zeeland, M. A.; Watkins, M. [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States); Cooper, C. M. [Oak Ridge Associated Universities, Oak Ridge, Tennessee 37830 (United States); Hollmann, E. M. [University of California-San Diego, 9500 Gilman Dr., La Jolla, California 92093-0417 (United States); Riso, V. [State University of New York-Buffalo, 12 Capen Hall, Buffalo, New York 14260-1660 (United States)

    2016-04-15

    A gamma ray camera is built for the DIII-D tokamak [J. Luxon, Nucl. Fusion 42, 614 (2002)] that provides spatial localization and energy resolution of gamma flux by combining a lead pinhole camera with custom-built detectors and optimized viewing geometry. This diagnostic system is installed on the outer midplane of the tokamak such that its 123 collimated sightlines extend across the tokamak radius while also covering most of the vertical extent of the plasma volume. A set of 30 bismuth germanate detectors can be secured in any of the available sightlines, allowing for customizable coverage in experiments with runaway electrons in the energy range of 1–60 MeV. Commissioning of the gamma ray imager includes the quantification of electromagnetic noise sources in the tokamak machine hall and a measurement of the energy spectrum of background gamma radiation. First measurements of gamma rays coming from the plasma provide a suitable testbed for implementing pulse height analysis that provides the energy of detected gamma photons.

  14. Experimental study of hydrogen jet ignition and jet extinguishment

    International Nuclear Information System (INIS)

    Wierman, R.W.

    1979-04-01

    Two phases are described of an experimental study that investigated: (1) the ignition characteristics of hydrogen--sodium jets, (2) the formation of hydrogen in sodium--humid air atmospheres, and (3) the extinguishment characteristics of burning hydrogen--sodium jets. Test conditions were similar to those postulated for highly-improbable breeder reactor core melt-through accidents and included: jet temperature, jet velocity, jet hydrogen concentration, jet sodium concentration, atmospheric oxygen concentration, and atmospheric water vapor concentration

  15. The JET Project (Design proposal)

    International Nuclear Information System (INIS)

    1976-01-01

    This proposal describes a large Tokamak experiment, which aims to study plasma behavior in conditions and dimensions approaching those required in a fusion reactor. The maximum plasma minor radius (a) is 1.25 m and the major radius R 0 is 2.96 m. An important feature is the flexibility to study, for plasma currents in the 1→3 MA range, a wide range of aspect ratios R 0 /a=2.37→5), toroidal magnetic fields (up to 3.6T), minor radii (0.6→1.25 m) and elongation ratios (b/a=1→3.5). The cost of the apparatus, power supplies, plasma heating equipment and specific diagnostics is estimated as 70.1 Muc (March 1975 prices, 1 uc=50 FB). The total construction phase cost including commissioning, buildings and staff is 135 Muc. These figures include an average overall contingency of 30%. The construction time for the project is estimated at 5 years and requires 370 professional man years of effort in the construction organisation with additional effort deployed by the Associated Laboratories in such areas as diagnostics and plasma heating. This design proposal is arranged as follows: The preface gives an introduction to the field of fusion research and relates JET to the European and international programmes. Chapter I is a concise summary of the design proposal, it describes the objectives of research with JET, and gives a brief description of: the apparatus; the cost and construction schedules; the proposed experimental programme and the possible modes of operation of the device. A detailed account of the project is given in the rest of the report of which Chapters IV and VII comprise the engineering design and the staff and cost estimates respectively

  16. Quark and gluon jet properties in symmetric three-jet events

    Science.gov (United States)

    Buskulic, D.; Casper, D.; de Bonis, I.; Decamp, D.; Ghez, P.; Goy, C.; Lees, J.-P.; Lucotte, A.; Minard, M.-N.; Odier, P.; Pietrzyk, B.; Chmeissani, M.; Crespo, J. M.; Efthymiopoulos, I.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, Ll.; Juste, A.; Martinez, M.; Orteu, S.; Pacheco, A.; Padilla, C.; Palla, F.; Pascual, A.; Perlas, J. A.; Riu, I.; Sanchez, F.; Teubert, F.; Colaleo, A.; Creanza, D.; de Palma, M.; Farilla, A.; Gelao, G.; Girone, M.; Iaselli, G.; Maggi, G.; Maggi, M.; Marinelli, N.; Natali, S.; Nuzzo, S.; Ranieri, A.; Raso, G.; Romano, F.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Zito, G.; Huang, X.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Alemany, R.; Bazarko, A. O.; Bonvicini, G.; Cattaneo, M.; Comas, P.; Coyle, P.; Drevermann, H.; Forty, R. W.; Frank, M.; Hagelberg, R.; Harvey, J.; Jacobsen, R.; Janot, P.; Jost, B.; Kneringer, E.; Knobloch, J.; Lehraus, I.; Martin, E. B.; Mato, P.; Minten, A.; Miquel, R.; Mir, Ll. M.; Moneta, L.; Oest, T.; Palazzi, P.; Pater, J. R.; Pusztaszeri, J.-F.; Ranjard, F.; Rensing, P.; Rolandi, L.; Schlatter, D.; Schmelling, M.; Schneider, O.; Tejessy, W.; Tomalin, I. R.; Venturi, A.; Wachsmuth, H.; Wildish, T.; Witzeling, W.; Wotschack, J.; Ajaltouni, Z.; Barrès, A.; Boyer, C.; Falvard, A.; Gay, P.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Monteil, S.; Montret, J.-C.; Pallin, D.; Perret, P.; Podlyski, F.; Proriol, J.; Rossignol, J.-M.; Fearnley, T.; Hansen, J. B.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Nilsson, B. S.; Wäänänen, A.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Siotis, I.; Vayaki, A.; Zachariadou, K.; Blondel, A.; Bonneaud, G.; Brient, J. C.; Bourdon, P.; Rougé, A.; Rumpf, M.; Tanaka, R.; Valassi, A.; Verderi, M.; Videau, H.; Candlin, D. J.; Parsons, M. I.; Focardi, E.; Parrini, G.; Corden, M.; Delfino, M.; Georgiopoulos, C.; Jaffe, D. E.; Antonelli, A.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Chiarella, V.; Felici, G.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Passalacqua, L.; Pepe-Altarelli, M.; Curtis, L.; Dorris, S. J.; Halley, A. W.; Knowles, I. G.; Lynch, J. G.; O'Shea, V.; Raine, C.; Reeves, P.; Scarr, J. M.; Smith, K.; Thompson, A. S.; Thomson, F.; Thorn, S.; Turnbull, R. M.; Becker, U.; Braun, O.; Geweniger, C.; Graefe, G.; Hanke, P.; Hepp, V.; Kluge, E. E.; Putzer, A.; Rensch, B.; Schmidt, M.; Sommer, J.; Stenzel, H.; Tittel, K.; Werner, S.; Wunsch, M.; Abbaneo, D.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Colling, D. J.; Dornan, P. J.; Moutoussi, A.; Nash, J.; San Martin, G.; Sedgbeer, J. K.; Stacey, A. M.; Dissertori, G.; Girtler, P.; Kuhn, D.; Rudolph, G.; Bowdery, C. K.; Brodbeck, T. J.; Colrain, P.; Crawford, G.; Finch, A. J.; Foster, F.; Hughes, G.; Sloan, T.; Whelan, E. P.; Williams, M. I.; Galla, A.; Greene, A. M.; Kleinknecht, K.; Quast, G.; Renk, B.; Rohne, E.; Sander, H.-G.; van Gemmeren, P.; Zeitnitz, C.; Aubert, J. J.; Bencheikh, A. M.; Benchouk, C.; Bonissent, A.; Bujosa, G.; Calvet, D.; Carr, J.; Diaconu, C.; Etienne, F.; Konstantinidis, N.; Nicod, D.; Payre, P.; Rousseau, D.; Talby, M.; Sadouki, A.; Thulasidas, M.; Trabelsi, K.; Abt, I.; Assmann, R.; Bauer, C.; Blum, W.; Brown, D.; Dietl, H.; Dydak, F.; Ganis, G.; Gotzhein, C.; Jakobs, K.; Kroha, H.; Lütjens, G.; Lutz, G.; Männer, W.; Moser, H.-G.; Richter, R.; Rosado-Schlosser, A.; Schael, S.; Settles, R.; Seywerd, H.; Denis, R. St.; Wiedenmann, W.; Wolf, G.; Boucrot, J.; Callot, O.; Cordier, A.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph.; Jacquet, M.; Kim, D. W.; Le Diberder, F.; Lefrançois, J.; Lutz, A.-M.; Nikolic, I.; Park, H. J.; Park, I. C.; Schune, M.-H.; Simion, S.; Veillet, J.-J.; Videau, I.; Azzurri, P.; Bagliesi, G.; Batignani, G.; Bettarini, S.; Bozzi, C.; Calderini, G.; Carpinelli, M.; Ciocci, M. A.; Ciulli, V.; Dell'Orso, R.; Fantechi, R.; Ferrante, I.; Foà, L.; Forti, F.; Giassi, A.; Giorgi, M. A.; Gregorio, A.; Ligabue, F.; Lusiani, A.; Marrocchesi, P. S.; Messineo, A.; Rizzo, G.; Sanguinetti, G.; Sciabà, A.; Spagnolo, P.; Steinberger, J.; Tenchini, R.; Tonelli, G.; Vannini, C.; Verdini, P. G.; Walsh, J.; Betteridge, A. P.; Blair, G. A.; Bryant, L. M.; Cerutti, F.; Chambers, J. T.; Gao, Y.; Green, M. G.; Johnson, D. L.; Medcalf, T.; Perrodo, P.; Strong, J. A.; von Wimmersperg-Toeller, J. H.; Botterill, D. R.; Clifft, R. W.; Edgecock, T. R.; Haywood, S.; Edwards, M.; Maley, P.; Norton, P. R.; Thompson, J. C.; Bloch-Devaux, B.; Colas, P.; Emery, S.; Kozanecki, W.; Lançon, E.; Lemaire, M. C.; Locci, E.; Marx, B.; Perez, P.; Rander, J.; Renardy, J.-F.; Roussarie, A.; Schuller, J.-P.; Schwindling, J.; Trabelsi, A.; Vallage, B.; Johnson, R. P.; Kim, H. Y.; Litke, A. M.; McNeil, M. A.; Taylor, G.; Beddall, A.; Booth, C. N.; Boswell, R.; Brew, C. A. J.; Cartwright, S.; Combley, F.; Koksal, A.; Letho, M.; Newton, W. M.; Rankin, C.; Reeve, J.; Thompson, L. F.; Böhrer, A.; Brandt, S.; Cowan, G.; Feigl, E.; Grupen, C.; Lutters, G.; Minguet-Rodriguez, J.; Rivera, F.; Saraiva, P.; Smolik, L.; Stephan, F.; Apollonio, M.; Bosisio, L.; Della Marina, R.; Giannini, G.; Gobbo, B.; Musolino, G.; Ragusa, F.; Rothberg, J.; Wasserbaech, S.; Armstrong, S. R.; Bellantoni, L.; Elmer, P.; Feng, Z.; Ferguson, D. P. S.; Gao, Y. S.; González, S.; Grahl, J.; Greening, T. C.; Harton, J. L.; Hayes, O. J.; Hu, H.; McNamara, P. A.; Nachtman, J. M.; Orejudos, W.; Pan, Y. B.; Saadi, Y.; Schmitt, M.; Scott, I. J.; Sharma, V.; Turk, J. D.; Walsh, A. M.; Wu, Sau Lan; Wu, X.; Yamartino, J. M.; Zheng, M.; Zobernig, G.; Aleph Collaboration

    1996-02-01

    Quark and gluon jets with the same energy, 24 GeV, are compared in symmetric three-jet configurations from hadronic Z decays observed by the ALEPH detector. Jets are defined using the Durham algorithm. Gluon jets are identified using an anti-tag on b jets, based on a track impact parameter method. The comparison of gluon and mixed flavour quark jets shows that gluon jets have a softer fragmentation function, a larger angular width and a higher particle multiplicity, Evidence is presented which shows that the corresponding differences between gluon and b jets are significantly smaller. In a statistically limited comparison the multiplicity in c jets was found to be comparable with that observed for the jets of mixed quark flavour.

  17. Control strategy for plasma equilibrium in a tokamak

    International Nuclear Information System (INIS)

    Miskell, R.V.

    1975-08-01

    Dynamic control of the plasma position within the torus of a TOKAMAK fusion device is a significant factor in the development of nuclear fusion as an energy source. This investigation develops a state variable model of a TOKAMAK thermonuclear device, suitable for application of modern control theory techniques. (auth)

  18. Alcator C-Mod Tokamak

    Data.gov (United States)

    Federal Laboratory Consortium — Alcator C-Mod at the Massachusetts Institute of Technology is operated as a DOE national user facility. Alcator C-Mod is a unique, compact tokamak facility that uses...

  19. Superconducting magnets and cryogenics for the steady state superconducting tokamak SST-1

    International Nuclear Information System (INIS)

    Saxena, Y.C.

    2000-01-01

    SST-1 is a steady state superconducting tokamak for studying the physics of the plasma processes in tokamak under steady state conditions and to learn technologies related to the steady state operation of the tokamak. SST-1 will have superconducting magnets made from NbTi based conductors operating at 4.5 K temperature. The design of the superconducting magnets and the cryogenic system of SST-1 tokamak are described. (author)

  20. Diagnostics systems for the TBR-E tokamak

    International Nuclear Information System (INIS)

    Ueda, M.; Ferreira, J.L.; Aso, Y.; Ferreira, J.G.

    1992-08-01

    A general view of the several diagnostics systems proposed for the TBR-E tokamak is given. This project is a joint undertaking of INPE, USP and UNICAMP plasma laboratories. The requirements for the measurements of the plasma produced parameters are described. Special attention is given for diagnostics used to investigate new physical issues on a low aspect ratio tokamak such as TBR-E. (author)

  1. Engineering Design of KSTAR tokamak main structure

    International Nuclear Information System (INIS)

    Im, K.H.; Cho, S.; Her, N.I.

    2001-01-01

    The main components of the KSTAR (Korea Superconducting Tokamak Advanced Research) tokamak including vacuum vessel, plasma facing components, cryostat, thermal shield and magnet supporting structure are in the final stage of engineering design. Hundai Heavy Industries (HHI) has been involved in the engineering design of these components. The current configuration and the final engineering design results for the KSTAR main structure are presented. (author)

  2. System studies for quasi-steady-state advanced physics tokamak

    International Nuclear Information System (INIS)

    Reid, R.L.; Peng, Y.K.M.

    1983-11-01

    Parametric studies were conducted using the Fusion Engineering Design Center (FEDC) Tokamak Systems Code to investigate the impact of veriation in physics parameters and technology limits on the performance and cost of a low q/sub psi/, high beta, quasi-steady-state tokamak for the purpose of fusion engineering experimentation. The features and characteristics chosen from each study were embodied into a single Advanced Physics Tokamak design for which a self-consistent set of parameters was generated and a value of capital cost was estimated

  3. Texas Experimental Tokamak

    International Nuclear Information System (INIS)

    Wootton, A.J.

    1990-04-01

    This paper discusses the following work on the text tokamak: data systems; particle confinement; impurity transport; plasma rotation; runaway electrons; electron cyclotron heating; FIR system; transient transport; internal turbulence; edge turbulence; ion temperature; EML experiments; impurity pellet experiments; MHD experiments and analysis; TEXT Upgrade; and Upgrade diagnostics

  4. Jet substructure using semi-inclusive jet functions in SCET

    International Nuclear Information System (INIS)

    Kang, Zhong-Bo; Ringer, Felix; Vitev, Ivan

    2016-01-01

    We propose a new method to evaluate jet substructure observables in inclusive jet measurements, based upon semi-inclusive jet functions in the framework of Soft Collinear Effective Theory (SCET). As a first example, we consider the jet fragmentation function, where a hadron h is identified inside a fully reconstructed jet. We introduce a new semi-inclusive fragmenting jet function G_i"h(z=ω_J/ω,z_h=ω_h/ω_J,ω_J,R,μ), which depends on the jet radius R and the large light-cone momenta of the parton ‘i’ initiating the jet (ω), the jet (ω_J), and the hadron h (ω_h). The jet fragmentation function can then be expressed as a semi-inclusive observable, in the spirit of actual experimental measurements, rather than as an exclusive one. We demonstrate the consistency of the effective field theory treatment and standard perturbative QCD calculations of this observable at next-to-leading order (NLO). The renormalization group (RG) equation for the semi-inclusive fragmenting jet function G_i"h(z,z_h,ω_J,R,μ) are also derived and shown to follow exactly the usual timelike DGLAP evolution equations for fragmentation functions. The newly obtained RG equations can be used to perform the resummation of single logarithms of the jet radius parameter R up to next-to-leading logarithmic (NLL_R) accuracy. In combination with the fixed NLO calculation, we obtain NLO+NLL_R results for the hadron distribution inside the jet. We present numerical results for pp→(jet h)X in the new framework, and find excellent agreement with existing LHC experimental data.

  5. Nonneutralized charge effects on tokamak edge magnetohydrodynamic stability

    International Nuclear Information System (INIS)

    Zheng, Linjin; Horton, W.; Miura, H.; Shi, T.H.; Wang, H.Q.

    2016-01-01

    Owing to the large ion orbits, excessive electrons can accumulate at tokamak edge. We find that the nonneutralized electrons at tokamak edge can contribute an electric compressive stress in the direction parallel to magnetic field by their mutual repulsive force. By extending the Chew–Goldburger–Low theory (Chew et al., 1956 [13]), it is shown that this newly recognized compressive stress can significantly change the plasma average magnetic well, so that a stabilization of magnetohydrodynamic modes in the pedestal can result. This linear stability regime helps to explain why in certain parameter regimes the tokamak high confinement can be rather quiet as observed experimentally.

  6. Relativistic runaway electrons in tokamak plasmas

    International Nuclear Information System (INIS)

    Jaspers, R.E.

    1995-01-01

    Runaway electrons are inherently present in a tokamak, in which an electric field is applied to drive a toroidal current. The experimental work is performed in the tokamak TEXTOR. Here runaway electrons can acquire energies of up to 30 MeV. The runaway electrons are studied by measuring their synchrotron radiation, which is emitted in the infrared wavelength range. The studies presented are unique in the sense that they are the first ones in tokamak research to employ this radiation. Hitherto, studies of runaway electrons revealed information about their loss in the edge of the discharge. The behaviour of confined runaways was still a terra incognita. The measurement of the synchrotron radiation allows a direct observation of the behaviour of runaway electrons in the hot core of the plasma. Information on the energy, the number and the momentum distribution of the runaway electrons is obtained. The production rate of the runaway electrons, their transport and the runaway interaction with plasma waves are studied. (orig./HP)

  7. The ICRH tokamak fusion test reactor

    International Nuclear Information System (INIS)

    Perkins, F.W.

    1976-01-01

    A Tokamak Fusion Test Reactor where the ion are maintained at Tsub(i) approximately 20keV>Tsub(e) approximately 7keV by ion-cyclotron resonance heating is shown to produce an energy amplification of Q>2 provided the principal ion energy loss channel is via collisional transfer to the electrons. Such a reactor produces 19MW of fusion power to the electrons. Such a reactor produces 19MW of fusion power and requires a 50MHz radio-frequency generator capable of 50MW peak power; it is otherwise compatible with the conceptual design for the Princeton TFTR. The required n tausub(E) values for electrons and ions are respectively ntausub(Ee)>1.5.10 13 cm -3 -sec and ntausub(Ei)>4.10 13 cm -3 -sec. The principal areas where research is needed to establish this concept are: tokamak transport calculations, ICRH physics, trapped-particle instability energy losses, tokamak equilibria with high values of βsub(theta), and, of course, impurities

  8. Spherical tokamak power plant design issues

    International Nuclear Information System (INIS)

    Hender, T.C.; Bond, A.; Edwards, J.; Karditsas, P.J.; McClements, K.G.; Mustoe, J.; Sherwood, D.V.; Voss, G.M.; Wilson, H.R.

    2000-01-01

    The very high β potential of the spherical tokamak has been demonstrated in the START experiment. Systems code studies show the cost of electricity from spherical tokamak power plants, operating at high β in second ballooning mode stable regime, is comparable with fossil fuels and fission. Outline engineering designs are presented based on two concepts for the central rod of the toroidal field (TF) circuit - a room temperature water cooled copper rod or a helium cooled cryogenic aluminium rod. For the copper rod case the TF return limbs are supported by the vacuum vessel, while for the aluminium rod the TF coils form an independent structure. In both cases thermohydraulic and stress calculations indicate the viability of the design. Two-dimensional neutronics calculations show the feasibility of tritium self-sufficiency without an inboard blanket. The spherical tokamak has unique maintenance possibilities based on lowering major component structures into a hot cell beneath the device and these are discussed

  9. Photoionization of Sodium Salt Solutions in a Liquid Jet

    International Nuclear Information System (INIS)

    Grieves, G. A.; Petrik, Nikolay G.; Herring-Captain, J.; Olanrewaju, B.; Aleksandrov, A.; Tonkyn, Russell G.; Barlow, Stephan E.; Kimmel, Gregory A.; Orlando, Thomas M.

    2008-01-01

    A liquid microjet was employed to examine the gas/liquid interface of aqueous sodium halide (Na+X-, X=Cl, Br, I) salt solutions. Laser excitation at 193 nm produced and removed cations of the form H+(H2O)n and Na+(H2O)m from liquid jet surfaces containing either NaCl, NaBr or NaI. The protonated water cluster yield varied inversely with increasing salt concentration, while the solvated sodium ion cluster yield varied by anion type. The distribution of H+(H2O)n at low salt concentration is identical to that observed from low-energy electron irradiated amorphous ice and the production of these clusters can be accounted for using a localized ionization/Coulomb expulsion model. Production of Na+(H2O)m is not accounted for by this model but requires ionization of solvation shell waters and a contact ion/Coulomb expulsion mechanism. The reduced yields of Na+(H2O)m from high concentration (10-2 and 10-1 M) NaBr and NaI solutions indicate a propensity for Br- and I- at the solution surfaces and interfaces. This is supported by the observation of multiphoton induced production and desorption of Br+ and I+ from the 10-2 and 10-1 M solution surfaces

  10. Photoionization of Sodium Salt Solutions in a Liquid Jet

    Energy Technology Data Exchange (ETDEWEB)

    Grieves, G. A.; Petrik, Nikolay G.; Herring-Captain, J.; Olanrewaju, B.; Aleksandrov, A.; Tonkyn, Russell G.; Barlow, Stephan E.; Kimmel, Gregory A.; Orlando, Thomas M.

    2008-06-05

    A liquid microjet was employed to examine the gas/liquid interface of aqueous sodium halide (Na+X-, X=Cl, Br, I) salt solutions. Laser excitation at 193 nm produced and removed cations of the form H+(H2O)n and Na+(H2O)m from liquid jet surfaces containing either NaCl, NaBr or NaI. The protonated water cluster yield varied inversely with increasing salt concentration, while the solvated sodium ion cluster yield varied by anion type. The distribution of H+(H2O)n at low salt concentration is identical to that observed from low-energy electron irradiated amorphous ice and the production of these clusters can be accounted for using a localized ionization/Coulomb expulsion model. Production of Na+(H2O)m is not accounted for by this model but requires ionization of solvation shell waters and a contact ion/Coulomb expulsion mechanism. The reduced yields of Na+(H2O)m from high concentration (10-2 and 10-1 M) NaBr and NaI solutions indicate a propensity for Br- and I- at the solution surfaces and interfaces. This is supported by the observation of multiphoton induced production and desorption of Br+ and I+ from the 10-2 and 10-1 M solution surfaces.

  11. EDITORIAL: The interaction of radio-frequency fields with fusion plasmas: the JET experience The interaction of radio-frequency fields with fusion plasmas: the JET experience

    Science.gov (United States)

    Ongena, Jef

    2012-07-01

    The JET Task Force Heating is proud to present this special issue. It is the result of hard and dedicated work by everybody participating in the Task Force over the last four years and gives an overview of the experimental and theoretical results obtained in the period 2008-2010 with radio frequency heating of JET fusion plasmas. Topics studied and reported in this issue are: investigations into the operation of lower hybrid heating accompanied by new modeling results; new experimental results and insights into the physics of various ion cyclotron range of frequencies (ICRF) heating scenarios; progress in studies of intrinsic and ion cyclotron wave-induced plasma rotation and flows; a summary of the developments over the last years in designing an ion cyclotron radiofrequency heating (ICRH) system that can cope with the presence of fast load variations in the edge, as e.g. caused by pellets or edge localized modes (ELMs) during H-Mode operation; an overview of the results obtained with the ITER-like antenna operating in H-Mode with a packed array of straps and power densities close to those of the projected ITER ICRH antenna; and, finally, a summary of the results obtained in applying ion cyclotron waves for wall conditioning of the tokamak. This issue would not have been possible without the strong motivation and efforts (sometimes truly heroic) of all colleagues of the JET Task Force Heating. A sincere word of thanks, therefore, to all authors and co-authors involved in the experiments, analysis and compilation of the papers. It was a special privilege to work with all of them during the past very intense years. Thanks also to all other European and non-European scientists who contributed to the JET scientific programme, the operations team of JET and the colleagues of the Close Support Unit in Culham. Thanks also to the editors, Editorial Board and referees of Plasma Physics and Controlled Fusion, together with the publishing staff of IOPP, who have not only

  12. Issues for the electric utilities posed by DT tokamak fusion powerplants

    International Nuclear Information System (INIS)

    Roth, J.R.

    1990-01-01

    The DT tokamak is the mainline approach to magnetic fusion energy in all industrialized countries with a major commitment to fusion research. It achieved this status largely through historical accident and not as the result of considered choice among alternatives. After twenty-five years of intensive tokamak research, it is appropriate to ask whether the path down which the tokamak concept is leading the fusion community is the way to an acceptable powerplant for the electric utilities, or an aberration which should be replaced with an approach more promising in the long term. Issues surrounding the DT tokamak can be grouped in three broad areas: physics; safety/environmental; and engineering/economic. In addition to these problems, detailed engineering design studies of DT tokamak fusion powerplants over a twenty year period have revealed a number of additional problems. Most of thee are related to the presence of tritium and energetic neutron fluxes, which tend to make the cost of electricity of DT tokamaks higher than that of fossil or fission powerplants. These safety and economic issues of the DT tokamak powerplant also appear to be intractable, and have not been made to go away by twenty years of progressively more detailed and extensive engineering design studies

  13. The 2.5-MeV neutron time-of-flight spectrometer TOFOR for experiments at JET

    International Nuclear Information System (INIS)

    Gatu Johnson, M.; Giacomelli, L.; Hjalmarsson, A.

    2007-08-01

    A time-of-flight (TOF) spectrometer for measurement of the 2.5-MeV neutron emission from fusion plasmas has been developed and put into use at the JET tokamak. It has been optimized for operation at high rates (TOFOR) for the purpose of performing advanced neutron emission spectroscopy (NES) diagnosis of deuterium plasmas with a focus on the fuel ion motional states for different auxiliary heating scenarios. This requires operation over a large dynamic range including high rates of >100 kHz with a maximum value of 0.5 MHz for the TOFOR design. This paper describes the design principles and their technical realization. The performance is illustrated with recent neutron time-of-flight spectra recorded for plasmas subjected to different heating scenarios. A data acquisition rate of 39 kHz has been achieved at about a tenth of the expected neutron yield limit of JET, giving a projected maximum of 400 kHz at peak JET plasma yield. This means that the count rate capability for NES diagnosis of D plasmas has been improved more than an order of magnitude. Another important performance factor is the spectrometer bandwidth where data have been acquired and analyzed successfully with a response function for neutrons over the energy range 1 to >5 MeV. The implications of instrumental advancement represented by TOFOR are discussed

  14. The 2.5-MeV neutron time-of-flight spectrometer TOFOR for experiments at JET

    International Nuclear Information System (INIS)

    Gatu Johnson, M.; Giacomelli, L.; Hjalmarsson, A.; Kaellne, J.; Weiszflog, M.; Andersson Sunden, E.; Conroy, S.; Ericsson, G.; Hellesen, C.; Ronchi, E.; Sjoestrand, H.; Gorini, G.; Tardocchi, M.; Combo, A.; Cruz, N.; Sousa, J.; Popovichev, S.

    2008-01-01

    A time-of-flight (TOF) spectrometer for measurement of the 2.5-MeV neutron emission from fusion plasmas has been developed and put into use at the JET tokamak. It has been optimized for operation at high rates (TOFOR) for the purpose of performing advanced neutron emission spectroscopy (NES) diagnosis of deuterium plasmas with a focus on the fuel ion motional states for different auxiliary heating scenarios. This requires operation over a large dynamic range, including high rates of >100 kHz with a maximum value of 0.5 MHz for the TOFOR design. This paper describes the design principles and their technical realization. The performance is illustrated with recent neutron TOF spectra recorded for plasmas subjected to different heating scenarios. A true event count rate of 39 kHz has been achieved at about a tenth of the expected neutron yield limit of JET, giving a projected maximum of 400 kHz at peak JET plasma yield. This means that the count rate capability for NES diagnosis of D plasmas has been improved more than an order of magnitude. Another important performance factor is the spectrometer bandwidth, where data have been acquired and analyzed successfully with a response function for neutrons over the energy range 1 to >5 MeV. The implications of instrumental advancement represented by TOFOR are discussed

  15. The 2.5-MeV neutron time-of-flight spectrometer TOFOR for experiments at JET

    Energy Technology Data Exchange (ETDEWEB)

    Gatu Johnson, M.; Giacomelli, L.; Hjalmarsson, A. (and others)

    2007-08-15

    A time-of-flight (TOF) spectrometer for measurement of the 2.5-MeV neutron emission from fusion plasmas has been developed and put into use at the JET tokamak. It has been optimized for operation at high rates (TOFOR) for the purpose of performing advanced neutron emission spectroscopy (NES) diagnosis of deuterium plasmas with a focus on the fuel ion motional states for different auxiliary heating scenarios. This requires operation over a large dynamic range including high rates of >100 kHz with a maximum value of 0.5 MHz for the TOFOR design. This paper describes the design principles and their technical realization. The performance is illustrated with recent neutron time-of-flight spectra recorded for plasmas subjected to different heating scenarios. A data acquisition rate of 39 kHz has been achieved at about a tenth of the expected neutron yield limit of JET, giving a projected maximum of 400 kHz at peak JET plasma yield. This means that the count rate capability for NES diagnosis of D plasmas has been improved more than an order of magnitude. Another important performance factor is the spectrometer bandwidth where data have been acquired and analyzed successfully with a response function for neutrons over the energy range 1 to >5 MeV. The implications of instrumental advancement represented by TOFOR are discussed.

  16. Magnet design considerations for Tokamak fusion reactors

    International Nuclear Information System (INIS)

    Purcell, J.R.; Chen, W.; Thomas, R.

    1976-01-01

    Design problems for superconducting ohmic heating and toroidal field coils for large Tokamak fusion reactors are discussed. The necessity for making these coils superconducting is explained, together with the functions of these coils in a Tokamak reactor. Major problem areas include materials related aspects and mechanical design and cryogenic considerations. Projections and comparisons are made based on existing superconducting magnet technology. The mechanical design of large-scale coils, which can contain the severe electromagnetic loading and stress generated in the winding, are emphasized. Additional major tasks include the development of high current conductors for pulsed applications to be used in fabricating the ohmic heating coils. It is important to note, however, that no insurmountable technical barriers are expected in the course of developing superconducting coils for Tokamak fusion reactors. (Auth.)

  17. Jets from jets: re-clustering as a tool for large radius jet reconstruction and grooming at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Nachman, Benjamin; Nef, Pascal; Schwartzman, Ariel; Swiatlowski, Maximilian [SLAC National Accelerator Laboratory, Stanford University,2575 Sand Hill Rd, Menlo Park, CA 94025 (United States); Wanotayaroj, Chaowaroj [Center for High Energy Physics, University of Oregon,1371 E. 13th Ave, Eugene, OR 97403 (United States)

    2015-02-12

    Jets with a large radius R≳1 and grooming algorithms are widely used to fully capture the decay products of boosted heavy particles at the Large Hadron Collider (LHC). Unlike most discriminating variables used in such studies, the jet radius is usually not optimized for specific physics scenarios. This is because every jet configuration must be calibrated, insitu, to account for detector response and other experimental effects. One solution to enhance the availability of large-R jet configurations used by the LHC experiments is jet re-clustering. Jet re-clustering introduces an intermediate scale rjets are calibrated and used as the inputs to reconstruct large radius jets. In this paper we systematically study and propose new jet re-clustering configurations and show that re-clustered large radius jets have essentially the same jet mass performance as large radius groomed jets. Jet re-clustering has the benefit that no additional large-R calibration is necessary, allowing the re-clustered large radius parameter to be optimized in the context of specific precision measurements or searches for new physics.

  18. Jets from jets: re-clustering as a tool for large radius jet reconstruction and grooming at the LHC

    International Nuclear Information System (INIS)

    Nachman, Benjamin; Nef, Pascal; Schwartzman, Ariel; Swiatlowski, Maximilian; Wanotayaroj, Chaowaroj

    2015-01-01

    Jets with a large radius R≳1 and grooming algorithms are widely used to fully capture the decay products of boosted heavy particles at the Large Hadron Collider (LHC). Unlike most discriminating variables used in such studies, the jet radius is usually not optimized for specific physics scenarios. This is because every jet configuration must be calibrated, insitu, to account for detector response and other experimental effects. One solution to enhance the availability of large-R jet configurations used by the LHC experiments is jet re-clustering. Jet re-clustering introduces an intermediate scale rjets are calibrated and used as the inputs to reconstruct large radius jets. In this paper we systematically study and propose new jet re-clustering configurations and show that re-clustered large radius jets have essentially the same jet mass performance as large radius groomed jets. Jet re-clustering has the benefit that no additional large-R calibration is necessary, allowing the re-clustered large radius parameter to be optimized in the context of specific precision measurements or searches for new physics.

  19. Mixing in Shear Coaxial Jets (Briefing Charts)

    Science.gov (United States)

    2013-08-01

    relevant boundary layers 9. Thermodynamic states (2 phase, 1 phase) 10. Transverse Acoustic mode from chamber/siren, f=f(c, geometry St=fDij/Uij 11...stability theory for inviscid instability of a hyperbolic tangent velocity profile for free boundary layers • U(y)=0.5[1 + tanh(y)] • Chigier and Beer , 1964...acoustics Natural OJ excited IJ excited From Chigier NA. and Beer JM, The Flow Region Near the Nozzle in Double Concentric Jets, J of

  20. Joint Czechoslovak-Soviet workshop on current drive in tokamaks

    International Nuclear Information System (INIS)

    1985-10-01

    At the Joint Czechoslovak-Soviet Workshop on Current Drive in Tokamaks, five papers dealing with issues of general interest were presented. In a theoretical paper by Klima and Pavlo a one-dimensional model of the lower-hybrid current drive is described and the results of its analysis are used in a numerical simulation using T-7 tokamak parameters. In the second theoretical paper by Vojtsekhovich, Parail and Pereverzev the influence of the LH wave spectrum on the efficiency of the current drive is studied. Two papers deal with a new microwave system designed for experiments on LHCD in the T-7 tokamak. In particular, the power spectra of new four-waveguide grills are computed. In the last paper the non-inductive start-up of the discharge in the T-7 tokamak by means of electron cyclotron waves is investigated. (J.U.)